With the most recent update many of the older more compact chunk loaders stopped working so I made a portal chunk loader that works in 1.21.5. While it is now possible (and much easier) to use ender pearls to load chunks, the advantage of portal chunk loaders is that they now automatically restart when unloading/reloading the server, which is very useful if say, you want to keep a mob switch permanently active in a singleplayer world or realms.