Panic Button users on macOS should take note!
There is an issue with the "Minimize All Windows" action that occurs if the "Open a new window after all browser windows are minimized" option is selected. If this action is invoked, and then the browser window states are restored by clicking the Panic Button toolbar button or pressing the keyboard shortcut on the temporary browser window, the restored browser window heights are shrunk down.
The shrunk-down browser windows after they are restored.
A similar issue happens when the Panic Button action is set to "Minimize Current Window."
This is confirmed to be occurring on Firefox versions 115 and 116 on macOS. This issue is not occurring on Windows.
The good news is that this issue is fixed in Firefox 117, which is due to be released at the end of August. Until then, consider turning off the option to open the temporary browser window, or change the Panic Button action to a different selection. This is understandably a bothersome inconvenience for many users -- indeed, Firefox 117 can't come soon enough!