You have 17 threads, so apologies if I asked this before, but have you tested in a new profile?

New Profile Test

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it.

Take a quick glance at the page and make a mental note of which Profile has this notation: This is the profile in use and it cannot be deleted. That is your current default profile.

Click the "Create a New Profile" button, then click Next. Assign a name like August2021, ignore the option to relocate the profile folder, and click the Finish button.

Firefox will switch your default profile to the new one, so click the Set as Default Profile button for your regular one to avoid an unwanted surprise at your next startup.

Scroll down to August2021 and click its Launch profile in new browser button.

Firefox should open a new window that looks like a brand new, uncustomized installation. (Your existing Firefox window(s) should not be affected.) Please ignore any tabs enticing you to connect to a Sync account or to activate extensions found on your system for now.

(1) Bookmark All Tabs

Open some tabs and try this feature (Ctrl+Shift+D).

If you check the Bookmarks Sidebar, did Firefox create the new folder with your bookmarked tabs?

If you close this window, wait 5 seconds, then launch the profile again and check the sidebar, did Firefox retain the bookmarks?

(2) Password Manager

You can test on my page here -- don't use any real user names or passwords, it's just for testing:

https://www.jeffersonscher.com/res/logintest.html

Does Firefox save and suggest logins?

If you close this window, wait 5 seconds, then launch the profile again and check the sidebar, did Firefox retain the bookmarks?

(3) Sync

So next try connecting the new profile to your Firefox Account by signing in from the menu. It takes some time to download the data, so I suggest leaving this window idle for 5 minutes.

What sync'd and what didn't?

When you are done with the experiment, you can close the extra window without affecting your regular Firefox profile. (August2021 will remain available for future testing.)

In case you were hoping that Bookmark All Tabs would also restore tabs after startup, they are not connected.

To restore session history, you need to use either:

• "3-bar" menu button > History > Restore Previous Session
• (menu bar) History > Restore Previous Session

If they are missing or grayed, check either:

• "3-bar" menu button > History > Recently Closed Windows
• "Library" toolbar button > History > Recently Closed Windows
• (menu bar) History > Recently Closed Windows

If that isn't possible because you clear history at exit...

To open tabs for the tabs you bookmarked, right-click the folder on the Bookmarks Menu or in the Bookmarks Sidebar and choose Open All in Tabs.

Before I do all this are we talking about firefox? If so then are you telling me that firefox works correctly and as advertised?

Well, I'm telling you how Firefox works. I am not sure what is going on with your Firefox yet.