For issues like this, please make a ticket in our discord https://discord.com/channels/940907977014120488/966592678768807946 . Someone has already reported this so it'll be looked into when someone has the time.
Went in game with Yin. Saw hand was there. Respawned fire giant using it. Giant died, hand stayed. Then spawned giant again, then hand disappeared. So seems like modpack issue with the fire giant summoner block. :(