Snapshot world corruption when leaving the nether

Hi, I tried to post my world file in the attachments but it wouldn't let me. So, My friend and I were playing on a new world on the newest snapshot + datapack for the caves and cliffs update. I set everything up today from scratch, had the world load, put the datapack in, reset the rest for a different seed but left the datapack in the world folder to avoid having to copy it in every time. Everything went perfectly until we went to the nether and died. Once we had respawned in the overworld we noticed an extreme amount of stuttering, and eventually figured out it only happened crossing chunk borders in the direction of spawn. So, I went to go look at spawn, and noticed the entire spawn region was now an ocean biome, but the terrain was the same as before. Loading any of these "ocean" chunks would freeze the game temporarily, but not the server. Restarting the server didn't fix it but it didn't make it worse either. I then went to see if anything weird had happened in the nether and everything was fine, so I teleported back to my friend in the overworld and then the entire world we had explored had the same thing happen to it, so our entire world is now a laggy ocean biome. I think it's somehow related to leaving the nether. The first time was from dying, the second was from teleporting out, I don't think leaving normally causes it but I didn't test it.