Mozilla has rolled out an emergency Firefox 139.0.1 update after the Tuesday release caused graphical artifacts on PCs with NVIDIA GPUs.

Firefox 139 shipped on May 27 with features like Full-Page Translations, but it also caused graphical artifacts when browsing the web in Firefox.

In a Reddit thread, several Firefox users complained that videos would flicker or flash. This issue also affects webpages, including sites like Instagram.

Mozilla has quickly identified the root cause and has shipped a hotfix with v139.0.1.

In a post on Bugzilla, Mozilla confirmed that Firefox 139 re-enabled a specific DirectComposition path behavior, which caused these issues.

In previous releases, Firefox kept a block list that stopped Firefox from using DirectComposition on mixed-refresh NVIDIA setup.

Unfortunately, the block list was removed with Firefox 139, and it allowed the browser to use DirectComposition in a way that exposed a graphics driver bug on NVIDIA cards under Windows 10.

When you play a 60 FPS video on the 60 Hz monitor and then scroll or hover over the content on the high-refresh monitor, parts of the video buffer leak into the other window.

That shows up as flashing artifacts or corruption wherever the page repaints. The issue doesn’t happen with 30 FPS content because the frame timing lines up with both refresh rates.

Single-monitor or AMD/Intel setups weren’t affected by these issues.

It is also worth noting that DirectComposition isn’t the problem, but Mozilla’s implementation clashes with certain GPUs.

“Currently the only thing that makes Firefox special in this respect is that it uses Windows DirectComposition in a certain way (Surfaces rather than Swapchains) for the majority of web content…” a Firefox developer noted in a post on Bugzilla.

“We have a new code path (the Layer Compositor as it is called) which should become available for testing in Firefox Nightly in the coming weeks if all goes well, we will have an interest in testing that on the same computers when it is ready, to verify if any of this flickering occurs with that approach which is much more similar to other browsers.”

Mozilla fixed artifacts in Firefox 139

As per the release notes, a new update (139.0.1) is now rolling out, and it restores the blocklist, which means you should no longer run into artifacts.

“Fixed graphics corruption with certain NVIDIA graphics adapters and multiple monitors running at mixed refresh rates after updating to Firefox 139,” Mozilla noted on the release notes page.

To install Firefox 139.0.1, open Settings and check for updates.