Chunks mixing up

So my hardcore world, where I've been playing in for months, just had a weird bug. All the spawn chunks and the chunks that i was loading when I opened the world seems to have mixed up. I didn't make a backup so all my progress is lost. I don't know if this is a bug in the game or its just my pc being stupid. Thought I put it here and see if you guys can maybe fix it for the new versions.