vBulletin 5.6.4 Patch Level 1
PHP 7.3.27
MySQL 10.2.38-MariaDB-cll-lve

I am having this strange issue. I cannot access admincp/index.php of any admin (super/admin) on certain browser (tried edge/chrome/chrome mobile).
Both me and the person I want to promote to admin have this issue. I can only login on my superadminstrator account only on Mozilla.

I have tried everything I could think of:
- different browser
- no browser extension
- change config.php cookies from bb to bb1 to bb again
- cleared all browser chace
- vpn
- mobile/router flush, reset
- http/https/www/no www

At the moment I am only using a language pack (i still have the issue if I change back to english) and Yilmaz - Usergroups Username Colors Everywhere vB5.

Nothing works. I can only login to those accounts AdminCP on mozilla.
What should I do?

This is the error I get (you can see an ad blocker which is turned off for the website, but I have tried even with the adblocker deleted and clean chrome install):