PHP 8 errors

The plugin breaks under PHP 8. For example these errors will break the site under PHP 8:

media-settings.php line 43: ‘create_function’ was removed in 8.0 PHP version
media-tags.php line line 48: ‘create_function’ was removed in 8.0 PHP version
media-tags.php line line 55: ‘create_function’ was removed in 8.0 PHP version
And there are also many undefined variable and undefined constant errors that will break under PHP 8.
This is the full error and warning report:

'Inspections Results' project 52 errors 99 warnings 27 weak warnings
PHP group 52 errors 99 warnings 27 weak warnings
Code smell group 9 warnings
Inconsistent return points inspection 9 warnings
file attachments-custom-fields.php 2 warnings
WARNING Missing return argument
WARNING Missing return argument
file file-gallery.php 1 warning
WARNING Missing return argument
file main.php 2 warnings
WARNING Missing return argument
WARNING Missing 'return' statement
file media-tags.php 1 warning
WARNING Missing 'return' statement
file TreeBuilder.php 3 warnings
WARNING Missing 'return' statement
WARNING Missing 'return' statement
WARNING Missing 'return' statement
Control flow group 1 warning
Unreachable statement inspection 1 warning
file mime-types.php 1 warning
WARNING Unreachable statement
General group 3 errors 2 warnings
Array index is immediately rewritten inspection 2 warnings
file media-settings.php 1 warning
WARNING Array index is immediately overwritten before accessing
file regenerate-images.php 1 warning
WARNING Array index is immediately overwritten before accessing
Element is not available in configured PHP version inspection 3 errors
file media-settings.php 1 error
ERROR 'create_function' was removed in 8.0 PHP version
file media-tags.php 2 errors
ERROR 'create_function' was removed in 8.0 PHP version
ERROR 'create_function' was removed in 8.0 PHP version
Probable bugs group 1 error 45 warnings
Empty index operator not supported for strings inspection 1 error
file main.php 1 error
ERROR '[]' operator not supported for strings
Expression result unused inspection 1 warning
file TreeBuilder.php 1 warning
WARNING Expression result is not used anywhere
Optional before required parameter inspection 2 warnings
file attachments.php 1 warning
WARNING Optional parameter is provided before required
file file-gallery.php 1 warning
WARNING Optional parameter is provided before required
Statement has empty body inspection 41 warnings
file attachments-custom-fields.php 2 warnings
WARNING Statement has empty body
WARNING Statement has empty body
file InputStream.php 1 warning
WARNING Statement has empty body
file Tokenizer.php 7 warnings
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
file TreeBuilder.php 31 warnings
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
WARNING Statement has empty body
Void function result used inspection 1 warning
file TreeBuilder.php 1 warning
WARNING 'void' method 'emitToken' result used
Type compatibility group 1 error 23 warnings
Arithmetic operation with unsupported operands inspection 1 error
file attachments-custom-fields.php 1 error
ERROR Unsupported operand types in '\unknown_type % int' will cause a PHP 8 TypeError
Incompatible return type inspection 3 warnings
file attachments-custom-fields.php 3 warnings
WARNING Return value type is not compatible with declared
WARNING Return value type is not compatible with declared
WARNING Return value type is not compatible with declared
Parameter type inspection 20 warnings
file attachments-custom-fields.php 3 warnings
WARNING Parameter '$count' type is not compatible with declaration
WARNING Parameter '$metadata' type is not compatible with declaration
WARNING Parameter '$post' type is not compatible with declaration
file templating.php 1 warning
WARNING Parameter 'wp_get_attachment_link($attachment?>ID)' type is not compatible with declaration
file Tokenizer.php 16 warnings
WARNING Parameter 'self::WHITESPACE' type is not compatible with declaration
WARNING Parameter '$mask' type is not compatible with declaration
WARNING Parameter 'self::ALPHA' type is not compatible with declaration
WARNING Parameter 'self::UPPER_ALPHA' type is not compatible with declaration
WARNING Parameter '"\t\n\x0C />" . self::UPPER_ALPHA' type is not compatible with declaration
WARNING Parameter 'self::UPPER_ALPHA' type is not compatible with declaration
WARNING Parameter '"\t\n\x0C /=>\"'" . self::UPPER_ALPHA' type is not compatible with declaration
WARNING Parameter ''"&'' type is not compatible with declaration
WARNING Parameter '"'&"' type is not compatible with declaration
WARNING Parameter '"\t\n\x0c &>\"'="' type is not compatible with declaration
WARNING Parameter ''>'' type is not compatible with declaration
WARNING Parameter ''?'' type is not compatible with declaration
WARNING Parameter 'self::ALPHA' type is not compatible with declaration
WARNING Parameter ''?'' type is not compatible with declaration
WARNING Parameter 'self::ALPHA' type is not compatible with declaration
WARNING Parameter '$char_class' type is not compatible with declaration
Undefined symbols group 47 errors 19 warnings 27 weak warnings
Undefined class inspection 16 warnings
file attachments-custom-fields.php 4 warnings
WARNING Undefined class 'unknown_type'
WARNING Undefined class 'unknown_type'
WARNING Undefined class 'unknown'
WARNING Undefined class 'unknown_type'
file attachments.php 1 warning
WARNING Undefined class 'echoes'
file file-gallery.php 1 warning
WARNING Undefined class 'Debug_Bar_Panel'
file InputStream.php 3 warnings
WARNING Undefined class 'Data'
WARNING Undefined class 'Bytes'
WARNING Undefined class 'Bytes'
file Parser.php 6 warnings
WARNING Undefined class 'HTML'
WARNING Undefined class 'Custom'
WARNING Undefined class 'Parsed'
WARNING Undefined class 'HTML'
WARNING Undefined class 'Custom'
WARNING Undefined class 'Parsed'
file Tokenizer.php 1 warning
WARNING Undefined class 'Data'
Undefined class constant inspection 1 error
file TreeBuilder.php 1 error
ERROR Constant 'INBODY' not found
Undefined constant inspection 1 error
file media-tags.php 1 error
WARNING Undefined constant 'MEDIA_TAGS_URL'
Undefined method inspection 3 warnings
file file-gallery.php 1 warning
WARNING Method 'title' is undefined
file regenerate-images.php 1 warning
WARNING Method 'get_error_message' is undefined
file TreeBuilder.php 1 warning
WARNING Method 'insertToken' is undefined
Undefined property inspection 4 weak warnings
file attachments.php 2 weak warnings
WARNING Property declared dynamically
WARNING Property declared dynamically
file TreeBuilder.php 2 weak warnings
WARNING Property declared dynamically
WARNING Property declared dynamically
Undefined variable inspection 45 errors 23 weak warnings
file attachments.php 2 weak warnings
ERROR Variable '$possible_new_attachments' is probably undefined
ERROR Variable '$promoted_id' is probably undefined
file file-gallery.php 1 error
ERROR Undefined variable '$acf_localize'
ERROR Undefined variable '$acf_options'
ERROR Variable '$transient' is probably undefined
file gallery.php 5 errors 1 weak warning
ERROR Undefined variable '$startcol'
ERROR Undefined variable '$endcol'
ERROR Undefined variable '$title'
ERROR Undefined variable '$thumb_link'
ERROR Undefined variable '$size'
ERROR Variable '$title' is probably undefined
file gallery.php 11 errors 1 weak warning
ERROR Undefined variable '$itemtag'
ERROR Undefined variable '$startcol'
ERROR Undefined variable '$endcol'
ERROR Undefined variable '$icontag'
ERROR Undefined variable '$title'
ERROR Undefined variable '$thumb_link'
ERROR Undefined variable '$thumb_width'
ERROR Undefined variable '$thumb_height'
ERROR Undefined variable '$size'
ERROR Undefined variable '$thumb_alt'
ERROR Variable '$title' is probably undefined
ERROR Undefined variable '$captiontag'
file gallery.php 11 errors 3 weak warnings
ERROR Undefined variable '$link'
ERROR Undefined variable '$file_gallery_this_template_counter'
ERROR Undefined variable '$link_class'
ERROR Variable '$link' is probably undefined
ERROR Undefined variable '$endcol'
ERROR Variable '$diff' is probably undefined
ERROR Undefined variable '$caption'
ERROR Undefined variable '$thumb_link'
ERROR Undefined variable '$thumb_width'
ERROR Undefined variable '$thumb_height'
ERROR Undefined variable '$title'
ERROR Undefined variable '$size'
ERROR Undefined variable '$thumb_alt'
ERROR Variable '$link' is probably undefined
file gallery.php 2 errors 1 weak warning
ERROR Undefined variable '$endcol'
ERROR Undefined variable '$title'
ERROR Variable '$title' is probably undefined
file main-form.php 10 errors 7 weak warnings
ERROR Undefined variable '$output'
ERROR Undefined variable '$checked_attachments'
ERROR Undefined variable '$delete_what'
ERROR Undefined variable '$post_id'
ERROR Undefined variable '$gallery_state'
ERROR Variable '$file_gallery_options' is probably undefined
ERROR Variable '$gallery_state' is probably undefined
ERROR Undefined variable '$sizes'
ERROR Variable '$templates_dropdown' is probably undefined
ERROR Variable '$templates_dropdown' is probably undefined
ERROR Undefined variable '$single_state'
ERROR Variable '$single_state' is probably undefined
ERROR Variable '$post_id' is probably undefined
ERROR Undefined variable '$files_or_tags'
ERROR Undefined variable '$attachment_orderby'
ERROR Undefined variable '$attachment_order'
ERROR Variable '$post_id' is probably undefined
file media-settings.php 2 errors 1 weak warning
ERROR Variable '$output' is probably undefined
ERROR Undefined variable '$values'
ERROR Undefined variable '$values'
file mime-types.php 1 weak warning
ERROR Variable '$out' is probably undefined
file templates-media-wp39.php 1 error
ERROR Undefined variable '$post'
file templates-media-wp40.php 1 error
ERROR Undefined variable '$post'
file templates-media-wp43.php 1 error
ERROR Undefined variable '$post'
file templating.php 1 weak warning
ERROR Variable '$transient' is probably undefined
file Tokenizer.php 1 weak warning
ERROR Variable '$id' is probably undefined
file TreeBuilder.php 4 weak warnings
ERROR Variable '$in_stack' is probably undefined
ERROR Variable '$fe_af_pos' is probably undefined
ERROR Variable '$fe_af_pos' is probably undefined
ERROR Variable '$fe_af_pos' is probably undefined