I am Very condused, I updated my game to the newest version (1.19.10) and continued playing normaly, I did notice that part of my railway to a pillager outpost were gone while I was building my massive Floating Island, I came closer to inspect why parts of these rails were gone, I then noticed that a massive part of the snowbiome was gone in a strait line and replaced with an ocean biome. In the Extrem Chunk Border Png one can see that the biome was a snowbiome( see the map my character is holding) until I updated to 1.19.10 this wasn't there. Now there is a Giant 2-3 Chunk wide ocean in my snow biome, This isn't a huge problem since I build nothing there execept that part of the railway, but I am still so confused how this even happened. The world I am playing in is active since minecraft 1.16.0, 1.16.1 or 1.16.2, I don't remember in which of these versions I created the world but it is almost 2-3 years old. Maybe the world is too old, but I never had real big chuck border Issues like this one up until 1.19.10 , I had some small ones like a small hill being cut of a little bit, but nothing huge like this.