Shulkers go to coordenates 0,0 when pass the end portal , but i sleep on a beed

I caught a shulker in the end and i transport the shulker to the end portal, 1500 blocks on a boat, y placed slaves arround, the shulker made tp on to a block, whit a piston i placed the shulker on end portal block and shulker went to overworld but surprised! he wasn't near my bed where i sleep, he was on 0,0 coordinates on water blocks in the middle of the sea, 100 block from my bed! ,  that's normal?

thank for solve the question.