Hi there,

Could you please try running Firefox in Troubleshoot Mode and see whether the problem persists?

hello Denys, if I go to troubleshoot mode the side bar goes light but when I restart it goes dark again

Is there a way to stay in troubleshoot mode or do I have to switch to it every time?

If the problem doesn't persist in Troubleshoot Mode, the likely cause is an extension, theme or hardware acceleration. Please see this article for further troubleshooting steps.

Problem solved. The culprit was the LiteFox theme, but it's a real bummer I've been using it since I use Firefox (probably more than 20 years) I have to find a way to contact the developer to see if he can fix the bug. Looks like he updated the version today. Thank You