If you're using PSO2 Tweaker try uninstalling and then installing it not through Tweaker. I did that with Steam and I've had 0 trouble with it since I switched.
I'm doing that right now. Whatever I tried before, didn't work (Or only temporarily). It still went on and off with the crashes. I had days where it didn't crash at all and then I had days (Like today) where talking to the first NPC already caused the game to stop responding after less than a minute. So now I'm gonna go for the "Screw it!" route. Uninstalling the game, removed anything I can find that was related to PSO2 and NGS and just reinstall the whole thing through the Tweaker alone. I did make some backups of the setting and character creation files, so at least I don't have to do all of that over again
I installed PSO2 through the Microsoft Store the first time around (Yeah... I had no other choice sadly). I can only hope that there was some leftover crap from that which was causing most of the issues. But we'll see
Update: Aaaand it didn't work. So reinstalling is out of the picture now, too