Minecraft eats memory

When playing the newest snapshot of minecraft, I have allocated 8GB of ram because i usually play with huge modpacks but I saw that the amount of ram just kept going up until It hit 8GB, had a huge lagspike, and reset. In the video I have provided, The lag spike happens and then the gme crashes while I'm typing.

https://youtu.be/-uMoC5S7Ha0