I created a survival world in 20w12a, and have been playing the same world using the new snapshots that get released. I'm boating through a river and suddenly my entire game freezes, I can't control my mouse and I force-reboot my computer. I launch the game and world again, and I'm still on my boat. Another random lag spike happens, and the game closes with the launcher showing an error: java.lang.UnsupportedOperationException. This behaviour just now started happening with 20w21a, but I had played on the snapshot the day before and everything worked perfectly fine.