[MC-178619] Can't normally save and exit a Minecraft world in the most recent snapshot

When I try to save and exit a world in 20w15, the game freezes, and makes a really high pitched sound, and my gpu fans ram up to 100%. This happens when exiting from the nether but also from the overworld. The only thing that I can do to exit the game now is to kill the process in system monitor. When I reenter the world it reverted back to it's original state(I have never been able to save this world)

How to reproduce:

Open a Minecraft world in the latest version and try to save it.

Environment

OS: Ubuntu 19.10
Specs:
Intel core i5 6400
Nvidia GeForce GTX 960
16Gb RAM (4Gb allocated to Minecraft)
128Gb SSD
2Tb HDD
Java version:
Java version 11
JVM arguments:
-Xmx4G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M