Hello,
Thank you for your suggestion.
I have already followed all the steps you mentioned — I deactivated all third-party plugins and kept only the theme-required plugins active. Even after doing this, the issue still persists.
Also, I would like to mention that all these plugins have been in use for quite a long time without any problem. This issue has appeared only recently.
Please let me know the next steps, or if you would like to check from your end, I can share the WP login details as needed.
Looking forward to your response.