PHP warnings

Hi, we have turned on debugging and only see the following warnings.

We have tested with 2022 theme and all other plugins deactivated.

Please could you advise us? Thank you.

Warning: session_start(): open(/var/cpanel/php/sessions/ea-php72/sess_9f99ccbdac7664b857df39be68b2b8b2, O_RDWR) failed: No such file or directory (2) in /home/sites/20b/2/2996d93d6b/public_html/wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php on line 145

Warning: session_start(): Failed to read session data: files (path: /var/cpanel/php/sessions/ea-php72) in /home/sites/20b/2/2996d93d6b/public_html/wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php on line 145

Warning: Cannot modify header information - headers already sent by (output started at /home/sites/20b/2/2996d93d6b/public_html/wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php:145) in /home/sites/20b/2/2996d93d6b/public_html/wp-admin/includes/misc.php on line 1381

Warning: Cannot modify header information - headers already sent by (output started at /home/sites/20b/2/2996d93d6b/public_html/wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php:145) in /home/sites/20b/2/2996d93d6b/public_html/wp-includes/functions.php on line 6878

Warning: Cannot modify header information - headers already sent by (output started at /home/sites/20b/2/2996d93d6b/public_html/wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php:145) in /home/sites/20b/2/2996d93d6b/public_html/wp-includes/pluggable.php on line 1421

Warning: Cannot modify header information - headers already sent by (output started at /home/sites/20b/2/2996d93d6b/public_html/wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php:145) in /home/sites/20b/2/2996d93d6b/public_html/wp-includes/pluggable.php on line 1424

Warning: Cannot modify header information - headers already sent by (output started at /home/sites/20b/2/2996d93d6b/public_html/wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php:145) in /home/sites/20b/2/2996d93d6b/public_html/wp-includes/pluggable.php on line 1421

Warning: Cannot modify header information - headers already sent by (output started at /home/sites/20b/2/2996d93d6b/public_html/wp-content/plugins/custom-sidebars/inc/external/wpmu-lib/inc/class-thelib.php:145) in /home/sites/20b/2/2996d93d6b/public_html/wp-includes/pluggable.php on line 1424

The page I need help with: [log in to see the link]