Shadow cursed bug

this game went over the course of months so my memory is hazy but a player decided to leave our 4 person game a few months ago when we were in the shadow lands, but just today someone else decided to take up his character (were level 12 in act 3 btw) and we killed him in our camp to resolve some other thing (we couldnt ft out of camp or long rest for some reason so they decided to kill him)

but when he died he came back to life with the shadow cursed condition and lost control of the character as he attacked us for some reason. im just here to report this bug to the best of my knowledge and see if its common or not