Modifying Max Height in Custom Worlds makes the game crash

As I soon as snapshot 20w49a was released, I decided to create a custom world with datapacks.
The datapack modified the Max Height paramater in order to modify the World Height Limit.
But when I changed it to a diferent number, when you open the world, game instantly crashes.

In Addition: sometimes when you change the parameters mentioned above, and enter the world, you won't see nothing but frozen entities around, and you won't be able to interact with the enviroment.

Thank you for reading.