You can be withered on normal difficulty, but not on hard and easy.
wither skulls hits are verry weak too.
a normal portal in the nether linked to a overworld portal higher than 128.
it's the overworld portal that need to be higher than 128.
I found this bug trying to transport villagers on a platform high in the sky.
my villagers disappears
II's related to the difficulty,, and not the servers.
Our servers are on hard, and my local test world was on normal.
That's why it was not happening on my local world.
But the fact that is was local was irrelevent.