User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:99.0) Gecko/20100101 Firefox/99.0

Steps to reproduce:

• On Ubuntu 21.10, set one monitor to 100% scale and another to 200% scale (as in the attached screenshot)
• Ensure layout.css.devPixelsPerPx is at -1.0 (the default) in about:config

Actual results:

Firefox windows stay at 1× scale regardless of which monitor they're on

Expected results:

Each window should switch between 1× on my 1080p monitor and 2× on my 2160p monitor when I drag it from one to the other. This worked until a few days ago; I'm not sure whether Firefox may have updated in the background.

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Gtk' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

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Thanks.

This is due to ubuntu going back to XWayland rather than Wayland in their snaps.

If I read https://gitlab.freedesktop.org/xorg/xserver/-/issues/1318 correctly, this is just a side effect of using XWayland and upstream has no fix yet. I dont see what we can do more there.