I'm on a 2017 Macbook Pro. I believe I was using Firefox 137.0 but have now gone back to the last saved update session file which is 133.0.3.

When I close Firefox, it clearly recognises all the open windows as it asks if I want to close all 6 windows. When I reopen Firefox it briefly shows all the windows in position but before it reopens all the tabs in those windows, 2 of them disappear. If I open a new tab and start typing something I know is in those missing windows it suggests "Switch to tab". If I click on that the current window dulls as if the requested window and its tabs have become active but the entire window is invisible. I have tried renaming xulstore and localstore and tried deleting xulstore entirely. Neither worked. It's possible that I hit some mental combination of shift, command and something near the 3 or 4 keys on the keyboard as I was trying to take a quick screenshot on a website before a pop up reappeared. This was the last session where everything was as it should be. I wish I hadn't gone back to the saved update session from December as its clear the app still recognises the windows are "there". I've reopened it so many times since having deleted tabs, cookies, whatnot that the session I was in before things went pear shaped is now long gone. If I click on the icon for recent browsing it shows 6 windows and I subsequently deleted some tabs from the missing windows that might've been an issue, were recent, or might use more power like Youtube or news sites. On restarting, the 2 missing windows remain invisible. In the words of Penelope Pitstop. "Hayulp!" Any guidance or tissues gratefully received.