Most of it seems to be visual only. I actually kind of like these quirks on the rare occasion I come across them. Same thing can happen with the Stormfiend’s flamethrower.
I’ve had the fire way more times than the vomit. It seems to happen when you load in the middle of a monster fight at just the right time when the attack is active. I join matches often so I probably come across them more than the average person.