[Environment:]

Mac 10.15
Ubuntu 20.04
Windows 10 x64

Firefox 92 beta 4
Nightly 93.0a1

[Steps:]

1. Open Firefox.
2. Create a new folder on the Bookmarks Toolbar.
3. Click on the created folder and observe its size.

[Actual Result:]

The bookmark submenu is too big.

[Expected Result:]

The size of the bookmark submenu shouldn't be that big.

[Notes:]

This issue is not reproducible on Firefox 91.

Found commit message:
Bug 1703051, apply proton panel styling to other bookmarks dropdown and overflow menu in bookmarks toolbar r=desktop-theme-reviewers,mconley,jaws,harry
pushlog_url: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=1e8ff38398ac6a98d0a0b5668a598206ed084688&tochange=9e5ec8c60805229571fb0b1a2b59f1fc53100cf2

:Gijs, I'm not sure if the dupe decision is correct. Bug 1722368 reports increased size of bookmark elements post-proton (90) - effectively reducing the amount of visible bookmarks, while this issue reports a further increase in element size for a specific situation(single elements), regressed by Bug 1703051 in 92.

(In reply to Adrian Florinescu [:aflorinescu] from comment #2)

:Gijs, I'm not sure if the dupe decision is correct. Bug 1722368 reports increased size of bookmark elements post-proton (90) - effectively reducing the amount of visible bookmarks, while this issue reports a further increase in element size for a specific situation(single elements), regressed by Bug 1703051 in 92.

We've brought the bookmarks subfolders in line with other panel UI, and the other dupes of bug 1722368 also complain about the panel UI in the hamburger menu, which was already the same size as the bookmarks UI is now. I don't think it makes sense to track them separately; if we're going to do something about it, it'll apply to all the bookmarks menu/panel-ish UI, including both the UI that became a bit bigger still in 92, and the UI that was already that big.