From github: https://github.com/mozilla-mobile/fenix/issues/17719.

Starting in version 84, each open page is displayed as a gray fill.
Navigation bar and preferences are displayed correctly.
The captured screenshot shows the correct image.

Device information:
Mecool Km1 AMLOGIC S905X3
Stock-ROM Android TV 10
Firefox 85.1.1, Firefox Beta 86.0.0-beta.1

Change performed by the Move to Bugzilla add-on.

This seems similar to https://bugzilla.mozilla.org/show_bug.cgi?id=1683936 which should have been fixed on 86.
Maybe something similar is needed for the " Mail-G31 MP2" that powers this also.

I don't think it's quite the same issue as that, as there is some stuff visible on the screen, it's just the wrong colours (and maybe missing quite a lot). But yeah, I think we need to disable webrender on Mali-G31 until we figure out the problem.

The main question for now is if any other GPUs are affected. There don't appear to be any others in the G3x series (only 31). And I assume the G5x ones are okay as they have at least an order of magnitude more users and no reports. So I think we're safe to just blocklist G31 for now.

A user reported completely broken rendering on their Mali-G31 device,
starting when webrender was enabled. Block webrender on Mali-G31
devices until the cause has been identified and fixed.

https://hg.mozilla.org/mozilla-central/rev/11052b40320c

Julien, we have another webrender bug on release unfortunately. It's very severe (unusable browser), but I think the number of Mali G31 users is fairly small (it seems to be designed for Android TV devices). So I would propose uplifting this to beta, and if there's going to be a point release then release too, but I'm not sure if it's worth driving one. Does that sound sensible?

I'm also going to look in to hooking up webrender on android to the downloadable blocklist, so that we hopefully don't get bitten by this again.

Please request uplift to beta and release, we might have a new fenix release build coming up.

Comment on attachment 9200613 [details]
Bug 1689947 - Disable webrender on Mali-G31 devices. r?aosmond

Beta/Release Uplift Approval Request

• User impact if declined: Unusable browser for users with Mali-G31 GPUs (mostly Android TV devices)
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Falls back to opengl layers gfx backend which is still well tested and in widespread use.
• String changes made/needed:

Comment on attachment 9200613 [details]
Bug 1689947 - Disable webrender on Mali-G31 devices. r?aosmond

Approved for 86 beta 6, thanks.

https://hg.mozilla.org/releases/mozilla-beta/rev/3ac63cf9586b

Comment on attachment 9200613 [details]
Bug 1689947 - Disable webrender on Mali-G31 devices. r?aosmond

approved for fenix 85.1.2

https://hg.mozilla.org/releases/mozilla-release/rev/1177ff0696af

== Change summary for alert #28679 (as of Mon, 08 Feb 2021 19:06:49 GMT) ==

Improvements:

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=28679

The change in this bug only affects android, comment 15 is likely unrelated.

The graph is really unstable in these alerts.
I will do more investigation

the alerts was triggered on beta by a multi commit patch and the regression is on one of the containing changes
https://treeherder.mozilla.org/jobs?repo=mozilla-beta&revision=3ac63cf9586bcc786acb6437a026ef26518b8c41&group_state=expanded&selectedTaskRun=A-89xhUUTPOqt6xrvwDsUw.0