Hello,
Thank you for contacting the support and sorry for any inconvenience that might have been caused due to that.
Please head over to WordPress Dashboard > Appearance > Theme Editor and check the specified line in your functions.php file to check the filter or code causing the issue.
It is unlikely to be Rank math however,assuming you are using the latest version of all the plugins and the themes (please update if not yet), it would seem like a conflict with one of the plugins or the theme you are using.
To determine that, please follow this troubleshooting guide:
https://rankmath.com/kb/check-plugin-conflicts/
Please let us know if you find the culprit.
Only the site admin would know and your users won’t be affected by this troubleshooting.
Looking forward to helping you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.
