I can’t speak for Jeroen, but I played around with the upstream builds (both 92 and 91) and my faulty profile a bit and managed to isolate the trigger combination for this: MOZ_ENABLE_WAYLAND=1 and setting layout.css.devPixelsPerPx to my preferred value of 1.2; either resetting layout.css.devPixelsPerPx to its default (-1.0), or running Firefox without MOZ_ENABLE_WAYLAND=1 will make the toolbar items work again. Here’s the graphics portion of my about:support.

So my steps to reproduce this are:

1. start Firefox with MOZ_ENABLE_WAYLAND=1
2. set layout.css.devPixelsPerPx to 1.2
3. click on the hamburger menu button

What I expect to happen:
For the hamburger menu content to show.

What happens instead:
The hamburger menu content flickers or doesn’t show at all.

Steps to reproduce

1. Open about:config
2. Search for autoplay in the settings
3. Set media.autoplay.default to 1 (”Block Audio”, which is the default)
4. Set media.autoplay.blocking_policy to 2
5. Open a Twitch VOD, for instance https://www.twitch.tv/videos/280106033
6. Try to unmute the video (either by clicking Twitch player’s speaker control button, or by dragging the accompanying volume slider)

What I expect to happen

For the audio to be unmuted.

What happens instead

The audio remains muted, and the volume control/indicator remains in the muted position.

I’m unmotivated to report this to Twitch, as I’m unsure about the precise meaning of media.autoplay.blocking_policy, and I currently don’t use the non-working value for it myself. Feel free to downprioritize this as you see fit, unless the original reporter is still affected. Here’s my downstream report over at Launchpad though, just for reference. (I’ll update it too.)

Hi Alex!

It does not appear to have been fully fixed by Firefox 88 for me at least, although the conditions have changed slightly, and the remaining broken behavior is now slightly different too.

First, to update my note above: media.autoplay.enabled.user-gestures-needed has been superseded by media.autoplay.blocking_policy, and setting the latter to 2 is now required to trigger the issue (as it manifests presently); with the setting at either 0 or 1 I haven’t been able to reproduce any variation of the issue.

Now, the video doesn’t get paused anymore, but the unmuting also does not work: clicking the muted indicator just always resets it back to muted, instead of actually unmuting.

I’m affected by this too, in Ubuntu 20.04 with Firefox 83.0+build2-0ubuntu0.20.04.1.

Tested nightly (85.0a1.en-US.linux-x86_64) with a clean profile, and the issue remains.

Steps to reproduce

1. Start nightly with ./firefox -no-remote -profilemanager
2. Create a new profile, select it and click Start Nightly
3. Open these three tabs (replacing the first-run tabs currently open):

• https://twitter.com/i/lists/222412094
• https://twitter.com/uusijani/
• https://twitter.com/i/lists/1245729655862280192

4. Open preferences, set Home to Custom URLs…, select ”Use current pages”
5. Close the window
6. Start nightly again with ./firefox -no-remote -profilemanager, select the previously created profile

What happens

None of the three tabs load any content. The firefox process also doesn’t end after closing this window with the non-working tabs, I have to Ctrl-C out of it.

Further info

Upon subsequent starts, Nightly does appear to correctly load the tabs, whereas for my main Twitter profile and FF 83.0 no amount of restarts seems to help; instead I have to open another tab and open m.twitter.com in it, then click on the home button to have the home tabs load (and close the first, still stuck set of home tabs).