I'm also running IOS 10.13. In the Firefox version just prior to this current one the drop down would reorder randomly, all windows being displayed in the drop down. This current version 108.0.2, does not display all the open windows in the drop do...
I seem to have found a work around. I'm running an older MacBook Pro, if you set a hot corner ---system preferences --- desktop & screen saver --- hot corners --- then set one corner to --- application windows, when you run the cursor to that corner...
I think it is worse with 108.0.2. The previous version would reorder the windows pull down menu randomly. This current version reorders and deletes windows. If I go to history and select restore recently closed windows, they come back until I sele...