Theme Style stuck at dark theme

We have weird problem with one of our LibreNMS installations. It is stuck with the dark theme.
Overriding via config.php didn’t help. Neither did clearing cache on browser and server side (php-fpm) help. Switching config to different themes doesn’t have any effect either.

  • System is on latest ‘release’ channel update
  • latest php 7.4 packages
  • Nginx running

Did someone experience a similiar problem? How to revert back to the default light theme?

Thanks!

Can someone help? Is this something that is fixed somewhere else than the config files?