Dissapearing animals (possibly entities idk) whenever i log back in to my world

So sometimes when i log into my world (even pre 1.18) my animals would just dissapear. And when i bred them all over again it was okay for a couple days then the same thing happened. And no it wasn’t bcz of too many mobs, when i tried the 3rd time and they disappeared when I logged back into my world and i had only 4. Pls fix