Main Toolbar of Firefox is missing after minimize/ restore, when Firefox tiled without title bar

[goebbe]

Distribution

Linux Mint 22.1 Cinnamon

Package version

6.4.8

Graphics hardware in use

No response

Frequency

Always

Bug description

Main Toolbar (tab-bar) of Firefox is missing after minimize/ restore, when the Firefox Window (without title bar) is tiled.

Steps to reproduce

• Open Firefox
• Configure Firefox to not show the "Title bar"
  • right click on the Toolbar, choose "Customize Toolbar", unselct "Title bar"
• Grap the Toolbar of firefox and draw it to one of the borders to snap / tile (i.e. Firefox for half of the screen)
• In Cinnamon Toolbar, click on the Firefox icon twice, to minimize / restore Firefox
• result: The main Toolbar of Firefox is not visible.

Expected behavior

Minimize / restore of the Firefox window should not have an effect on the Main Toolbar of Firefox.

Additional information

This issue appeared first some days ago - and can be consistently reproduced on my computer.
I use snap / tiling frequently.

This issue does not appear, when the Firefox Window is not snapped/ tiled.
This issue does not appear, when the Title Bar of Firefox is shown.

Workaround:
If the Toolbar is missing after "Restore", it is sufficient to "Unmaximize" the Firefox Window to get the Main Toolbar back.

[Nextnx]

Same here, when anchored and minimized, on restored tabs are missing. Any resizing of the window will restore the tabs.
screenshot Discord on left side for reference.

[drinfohouse]

Same here.

[Tobias-Doerner]

Same here on one of my computers on Linux Mint 22.1 Cinnamon with current Firefox 138.0.3 but the second computer with also Linux Mint 22.1 Cinnamon running works fine with the same firefox version.

[goebbe]

I just tested Cinnamon using the "experimental Wayland support".
The issue with the missing Firefox toolbar/ title bar does not appear under Wayland.
So this seems to be an issue with x11 only.