Lack of documentation aside, one of the most common causes of a crash in XIV is if you try to switch sound sources. It's been a known problem since 2.0 has launched that XIV just can't handle a graceful hot swap of sound output. It managed to cause my 3080 Ti to choke and die the last time I forgot about the problem.

You will not get an error message, usually. The FPS will just drop to miserable levels and the sound will abrubtly shut off.

Since the OP's issue is happening really randomly, this probably isn't it, but I'm just tossing this in here because it's caused me to crash many times, and other people too.