Can't restore closed Safari tabs on Catalina! I have a big problem with Safari.  I had about 30 tabs opened and I restarted my computer. 

Safari opens itself empty, without restoring any tabs and the "restore all tabs from previous session" is disabled.

I searched the solution for hours.  The fix seems to be restoring an older version of the file LastSession.plist from the Library folder with Time Machine.  However, this isn't working on Catalina as Time Machine isn't working with this folder and its files.

Anyone know a workaround? I had really important tabs
At the top of the Safari page is a History Menu item. When you open that it should list the most recent sites you have visited. You may be able to recover them one at a time by clicking on each site. If no sites are listed I'd look for the plist file and edit it to see what is in it. I think TextEdit will open plist files. If not try Xcode.