Well not exactly. Tab suspenders (at least the ones I use) dump the current DOM state, etc to disk so when you reload the tab, it reloads it in mostly the same state it was in when you left it. Of course some pages don't like that and force a full refresh but generally I find when I get a tab reload on a documentation page when it loads back up I end up at roughly the same part of the page I was on when I left off.
It seems to work across restarts from what I can tell. I just tried to verify it.
I have a tab group in Simple Tab Groups for a perl project I've been working on. The group is basically just a bunch of perl docs (metacpan, etc). I haven't touched the project or the group in a few weeks and I've in that time restarted both FF and my PC several times as well as having updated my FF install several times.
I just switched to that tab group and opened up a random cpan docs tab and it loaded it back in half way down the page. The scroll moved a little bit (only a few lines of text worth of scroll) but that was it.
Of course this doesn't work consistently for all pages. I know for a fact that social apps like bluesky don't tolerate suspends all that well and force a reload but most "vanilla" web pages like docs sites tolerate suspends quite well.
