My villagers and animals despawned...

During a personal game, in survival, I noticed such a mistake.
I built a village near my house, surrounded it with a high stone wall and illuminated it well. Then I brought and multiplied the inhabitants. I closed all the exits from the village. I myself went through the stairs on the wall. From above, I covered the wall with half-blocks. Nearby, I built a mob farm, rising next to my village (not above it, but on the side at a distance of 15-20 blocks) up by 100-120 blocks somewhere (I don't remember the exact number).

After standing a game night on the farm, I went downstairs and found that my village was empty. Both adults and children have disappeared. All adult residents were traded and professed. I did not find any traces of any mobs.

I also made myself pens with cows, sheep and chickens. Today, having entered the game, I found that more than half of the animals were despawned in my pens. I have placed the pens in the underwater base, the spawn of hostile mobs there is completely excluded. The animals could not escape from the corrals, since the corrals are fenced with hatches and their bottom is sunk one block down. That is, the fence from the hatches is located above the pit in one block, in which the animals are.

At the same time, after my trip to the nether and traveling around the world for 8 thousand blocks, the animals and inhabitants did not despawn.

Everything happened either when I was in the game somewhere nearby, in a small radius, or when I entered the game at the base the next day.

What could be the reason?
Will this be fixed?

After all, building farms in survival with such a bug becomes very problematic. I play without cheats, I don't use bugs. All resources are obtained by honest labor.

My device: xiaomi 9t, 6 gb of RAM

upd: I just entered the game and found out that a cow with a tag has despawned me ... Omg ... I'm confused ...