Plugin version is 2.3.6 and wordpress version is 6.4.2
However, I have rectified the issue.
In the file
/wp-content/plugins/wck-custom-fields-and-custom-post-types-creator/wordpress-creation-kit-api/wordpress-creation-kit.php
Inside wck_get_entry_field_upload function if I remove esc_html from the thumbnail on line 678 then it fixes the issue.
Hope the next plugin update will fix this issue.
