Coming back to the issue.

Tonight I had 3 game crashes during Kefka Savage, all with no background programs running except Discord. I also did a fresh install earlier today for making sure it was not the game files. It was all fine for some 3 hours but during a break I teleported to Uldah and was immediately greeted with a windows-crash notification (this time it wasnt a dx11 error, just the typical Windows has encountered an error-thing).
After that it was fine until break was over and went back for Kefka. During the fight it kept crashing 2 times in 15 minutes, and then started to be fine again.
I'm using win10, latest updates. Not sure if it matters but I have XIV on my 2nd SSD (not the main drive).