e.g. nimbus ray will hit the zombie you are possessing (and by extension, yourself). Not sure if intended. It kind of makes a cool interaction (by possessing a body you lose your holiness until you regain living flesh kind of feel) but it's probably a bug so I'll drop it here.

Most likely nothing I can do about it but link me the other mod so I can look into its source later.

https://github.com/Ladysnake/Dissolution
I haven't poked too deeply into the code but from what I can see it simply assigns the spirit as riding the possessed entity? I haven't tried firing nimbus rays on horses yet actually, but I suspect something similar will result if you ride a large enough mob.