@tabbycat687 a clean install of my gpu drivers fixed it. They where up to date but after reinstalling them the text became readable again

I have the same issue since 22 June 2023. It is for every website, all these website do work in other browsers. I am currently writing this in firefox because my Opera GX browser is unusable.

My system is: Windows 10, 64bit, build 19045.3086. GPU drivers are up to date, Opera auto updated to the latest version, no idea which number that is because the settings page is unreadable.

I read about problems like this from several years ago and tried all the tricks mentioned there but nothing helps. Any help would be appreciated.