Hello Mate,
I have reviewed the errors you are experiencing on the admin page of your WordPress site. The warning messages indicate a permission issue and a header modification problem, both related to the LearnDash WooCommerce and LearnDash LMS plugins.
To better understand the situation, may I ask: Have you recently updated any plugins, themes, or WordPress core? And, have you made any changes to your server's file permissions or server configuration?
Best Regards,
Syed U.