Using Firefox 145.0 (64-bit), "Firefox is up to date" on PC with Windows 11 Pro.

I was so pleased when Firefox's Group Tabs arrived. I often have about 12 tabs open to do Railway research. So I thought, Group Tab, great idea. Save a group of tabs as one tab. Instead of creating a Bookmark Folder and each time opening all bookmarks from said folder, what better way to do than opening one tab. Or so I thought. I also created a "SHIP" tab for my hobby in the shipping industry, so I could have two group tabs that could be collapsed making the tab bar tidier. I saved an closed each group tab then closed down my PC. Next on restarting, Firefox starts up automatically as chosen by me. Both RAIL & SHIP tabs reappeared without me doing anything. Great! However yesterday, I inadvertently opened another Firefox window, forgot it was opened. So when I shut down my PC, I closed the Firefox browser and then discovered the over Firefox window I had opened. Closed it shut down my computer. Of course when I opened my PC today, Firefox started automatically, but with the tab that I had open in the last Firefox window. No problem I thought, I will just open the saved Group Tabs. It was a problem, where are the Group Tabs saved? Could I find the location? NO! I looked in Bookmarks, all the various History lists, even the down arrow to list all tabs. Nothing, the Group Tabs are none existent. I have checked on the "about:config" section for Group Tabs and everything is enabled "true". So where are the Group Tabs saved? I have been with Firefox for around 14 years, often citing it as the best browser. But over the last five years I find myself using Chrome more and more. Chrome has Group Tabs which do not not need the users to save them, they are saved automatically, and are easily found on opening the Chrome browser. Why doesn't Firefox have this?