Passive mob despawning

This issue started since the las update, which was the 1.17.30, as soon as I was entering my world to play as usual I started to notice that I was missing some important thing I had. This bug has been so annoying 'cause due to this bug I have lost more than 15 skeleton horses(which are really rare to see), 3 naturally spawned pink sheeps, all my dogs and cats , 2 brown pandas and finally some armor stands with some enchanted armor.

I don't see any reason for this to happen, is frustrating to think that I can't keep any special mobs in my base 'cause they will probably despawn and so then it is pointless