I'm seeing a magenta overlay over videos (in Twitter, but also previews on Netflix).

Firefox 85 (20201129092505), macOS 10.15.7 (19H2), macbook pro with Intel Iris Graphics 550.
I assumed it started after the last update.

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Updated from 20201126212448 (first to 20201127155321, then 20201129212213) on another macbook 13 with Intel Iris Plus Graphics 650, same problem.

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=ff2a53ac9e8ba797b2c4c88dc97009cc03caed15&tochange=b2d438ba2bdd2f2098ce1d4b3be1fd66c7eecf46

It seems to be bug 1678924, not sure if it's a dupe of bug 1678903 at this point (it doesn't look like, given how long that's been around).

Set release status flags based on info from the regressing bug 1678924

This might be a regression on Gen9 Skylake from the Gen6 fix.

Flod, mind posting your about:support text?

This is from the work computer (Iris 650, MacBook Pro (13-inch, 2017, Four Thunderbolt 3 Ports))

Also, worth noting that this doesn't happen on YouTube, for example. So far, I've seen it in on Twitter and Netflix (only for the previews when hovering an element). If it helps, I can provide also the about:support from the other machine.

Here is another about:support info from my MacBook Pro 2018 with Intel UHD Graphics 630 which is also affected.

I can't reproduce this on a UHD Graphics 630 running 10.15.6

I can see the same problem with Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:85.0) Gecko/20100101 Firefox/85.0 ID:20201130093031 and Intel Inc. -- Intel(R) Iris(TM) Plus Graphics 655.

For confirmation I run mozregression and found bug 1678924 being the culprit here:

 6:06.70 INFO: Narrowed integration regression window from [ff2a53ac, bc148cb7] (3 builds) to [ff2a53ac, b2d438ba] (2 builds) (~1 steps left)
 6:06.70 INFO: No more integration revisions, bisection finished.
 6:06.70 INFO: Last good revision: ff2a53ac9e8ba797b2c4c88dc97009cc03caed15
 6:06.70 INFO: First bad revision: b2d438ba2bdd2f2098ce1d4b3be1fd66c7eecf46
 6:06.70 INFO: Pushlog:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=ff2a53ac9e8ba797b2c4c88dc97009cc03caed15&tochange=b2d438ba2bdd2f2098ce1d4b3be1fd66c7eecf46

I started to try pushes:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=7c6fce7ae9870de98c94bffd4f07570fe1f47995
https://treeherder.mozilla.org/#/jobs?repo=try&revision=c7f908a948867267b30e7633c6742fae8dac6255
that have parts of the fix from bug 1678924 applied.

I'm also seeing this on my 16 inch 2019 Macbook Pro on some but not all Twitter videos and a few other places. Here's an example where I see it, because it looks like one hasn't been posted yet: https://twitter.com/catsdotexe/status/1333268668755668992 (if you click play, it goes magenta)

(In reply to Jeff Muizelaar [:jrmuizel] from comment #13)

I started to try pushes:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=7c6fce7ae9870de98c94bffd4f07570fe1f47995

This build seems to work correctly for me (at least, Twitter does).

https://treeherder.mozilla.org/#/jobs?repo=try&revision=c7f908a948867267b30e7633c6742fae8dac6255

This still has the issue.

Used this tweet as a test https://twitter.com/firefox/status/1333436877861433347

I can reproduce it my setup with https://twitter.com/catsdotexe/status/1333268668755668992

We've encountered similar bugs before, e.g.
https://github.com/servo/webrender/wiki/Driver-issues#3540---mac-glsl-compiler-bug-with-integer-comparison-take-two

We don't want to change this if to a switch because glsl-opt compiles it
down to an if statement anyway, just a more complicated one (which was triggering
other bugs on other platforms, see bug 1678924).

Backed out changeset fdf86dfacb7c (bug 1679700) for Build bustages. CLOSED TREE

Log:
https://treeherder.mozilla.org/logviewer?job_id=323067325&repo=autoland&lineNumber=2829

Push with failures:
https://treeherder.mozilla.org/jobs?repo=autoland&group_state=expanded&revision=fdf86dfacb7ca6116997bf925d748a7d347853e7

Backout:
https://hg.mozilla.org/integration/autoland/rev/3a5792f81151c8625b10fa21a39be9f290ebe195

For the record: This happens to me on Google Meet.

https://hg.mozilla.org/mozilla-central/rev/5d4b227d3b5c

Confirming the fix for Nightly 85.0a1 (2020-12-01). Google Meet works again. Thank you!

Comment on attachment 9190342 [details]
Bug 1679700 - Cast int parameter in get_yuv_offset_vector to float, to work around a shader compilation bug with integer equality comparisons on macOS Intel. r=jrmuizel

Beta/Release Uplift Approval Request

• User impact if declined: Magenta video on macOS
• 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: Bug 1678924
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): This only risk here is other shader compiler bugs. That's not very likely.
• String changes made/needed:

Comment on attachment 9190342 [details]
Bug 1679700 - Cast int parameter in get_yuv_offset_vector to float, to work around a shader compilation bug with integer equality comparisons on macOS Intel. r=jrmuizel

Approved for 84.0b7.

https://hg.mozilla.org/releases/mozilla-beta/rev/ead3393407f8

== Change summary for alert #28015 (as of Tue, 08 Dec 2020 12:35:54 GMT) ==

Improvements:

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=28015

Isn't that a Mac specific issue? How could this have been caused performance improvements on Android? The graph shows lot of jumps up and down, and since recently isn't that stable anymore. I get the feeling that a different patch actually caused that.

Did some rebuilds will come back with a result

I agree with Henrik that this bug is not the cause of the improvement.
as there are some issues running the test in the commits around this bug and that the grephs came back to the before value I ill mark this as a infrastructure issue.
Please ignore the previous alert comment