Player builds disappear

Very fatal error, everything made up by player suddenly gone for no reason. Let me say, everything still normal in second before, then suddenly disappear when I back and catch up villager. Everything, even bedrock is GONE, the nearby nether portal are spawned in different location, everything remains is living creature. It just like chunks are re-created and I don't know what to reach this error. Or maybe its because I reach to nether then small chance for this error? One more thing, my old build from 1.21.44 that ain't disappeared but only happens to my new build from 1.21.55. This is some pictures that I had take before and after the trouble.