When in a non-main Nether world, Nether portal destinations default to the main Nether world. This causes the search radius to be reduced from 128 to 16 (128 / 8).

While this is not an issue by itself, it causes an issue for Multiverse-NetherPortals, which sets the destination world to the non-main Nether world's corresponding Overworld. The issue is now that the search radius remains reduced. While this can be solved in Multiverse-NetherPortals, I think it would be a better idea to simply send all Nether portals in any Nether world to the main Overworld, that way the search radius is not scaled by default.

My suggested change is the following:
On line 504 of Entity.patch (https://hub.spigotmc.org/stash/projects/SPIGOT/repos/craftbukkit/browse/nms-patches/Entity.patch#504), change

ResourceKey<World> resourcekey = this.world.getDimensionKey() == World.THE_NETHER ? World.OVERWORLD : World.THE_NETHER;

to

ResourceKey<World> resourcekey = this.world.getTypeKey() == DimensionManager.THE_NETHER ? World.OVERWORLD : World.THE_NETHER;