User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:87.0) Gecko/20100101 Firefox/87.0
Steps to reproduce:
Open firefox with some tabs (like 15 or more), the more the better. I have a lot of youtube tabs and some webpages llike computerbase open. Drag one tab out to create a new window with the tab. Now open tabs in that new window. Now just browse for some minutes and close all tabs in the newly created window. After some time hovering will not work as expected and it is impossible to drag out a tab into a new window like done before. A restart of the browser fixes the issue temporarily till it occures again.
Distribution: Fedora 33
Desktop: Gnome 3.38.4
Firefox Version: 87
Package: Flatpak and rpm Package from Distribution
Kernel Version: 5.11.8
Graphics Drivers: Mesa 20.3.4
Hovering an the webpage and the bookmarks bar does not work anymore. When hovering bookmark folders, they don't open anymore. You have to click them manually. It is also not possible to drag a tab out of the window to create a new window with the dragged tab. It just does not work anymore.
The dragging out of tabs in a window works all the time and hovering should not be broken.