The set of open tabs at closing are stored in session.json. If it becomes corrupted, close TB, open the profile folder, delete or rename the json file, then restart TB a few times and see if the tab set is retained.

Check also that you don't have an app like CCLeaner that resets some TB settings.

no didn't work

I seem to have solved it maybe I found I had both the deb and the snap installed at the same time (Ubuntu 24.04) uninstalled the deb and so far so good

not solved tried everything ah well

Have you tried with a new profile and no additions except one account? Help/Troubleshooting Info, about:profiles. If it works, transferring data from the old profile to the new one is often a lot faster than trying to debug the old one.

Trying now, good so far

looks like this is solved, thanks

Have you tried with a new profile and no additions except one account? Help/Troubleshooting Info, about:profiles. If it works, transferring data from the old profile to the new one is often a lot faster than trying to debug the old one.

this did it this is the soln

I cannot close this, the link doesn't work https://support.mozilla.org/en-US/questions/1454844/solve/1665064?watch=DPYhZybjWv&utm_campaign=questions-reply&utm_source=notification&utm_medium=email

You apparently have already marked one of your replies as the solution. I think only the OP (you) can undo marking and mark another post as the solution. Of course, it can also be done by a forum admin.