Green artifacts appear on the scrollbar while scrolling some webpages

[mcbalaam]

Preliminary Checks

• I have read and understood the important section above.
• I have searched existing issues and avoided creating duplicates.
• I am not filing an enhancement request.
• I have checked that this issue cannot be reproduced on Mozilla Firefox.
• I have checked that this issue can be reproduced once I removed all my Mods and Custom CSS.

What happened?

2025-10-10.23-25-41.mp4

I'm assuming it has something to do with the custom scrollbar CSS, but I was unable to reproduce this behavior in other browsers

Expected behavior

The scrollbar would just scroll

Actual behavior

There are... green squares flickering on top of the scrollbar

Steps to reproduce

1. Open the Perplexity chat page https://www.perplexity.ai
2. Chat for a while
3. Try scrolling
4. :tuh:

Screenshots and videos

No response

Version

1.16t (Firefox 144.0) (2025-10-08)

What platform are you seeing the problem on?

Windows - x64

What component is this issue related to?

Tabs

Relevant log output if applicable

[Propheticus]

I'm assuming it has something to do with the custom scrollbar CSS

Have you tried to confirm by testing without the custom CSS? You ticked the checkbox of the preliminary check, but it sounds like you did not.

[mcbalaam]

I'm assuming it has something to do with the custom scrollbar CSS

Have you tried to confirm by testing without the custom CSS? You ticked the checkbox of the preliminary check, but it sounds like you did not.

Custom scrollbar CSS as in CSS defined by the website. I read what I click

[Propheticus]

Had to check, sorry. Many don't.

Can you perhaps share the report from about:support ? (can be entered like a URL)

[Propheticus]

Firefox does not support scrollbar CSS customisation other than the 2 web standard options to set track width and thumb colour.

Those green blocks look like GPU driver (hardware acceleration) corruption. I can't reproduce them on Windows.
My first suggestion would be to check and update your GPU drivers.