No Dim (Formerly No End): The simplest anti-dimension mod

This mod simply disables the collision of end/nether portals in order to prevent players going to that dimension.

Admins can use /gamerule disableEnd or /gamerule disableNether in order to toggle the mod.

The mod has only been tested on 1.20.x - 1.21, however it most likely would work on other versions as well.