Shulkers going through a nether portal without a valid teleportation spot would ignore dimension scaling, and would remain in the coordinates of their previous dimension.

If a shulker from overworld X: 12345, Y: 70, Z: 5514 travels through a nether portal but there isn't a surface for the shulker to teleport to, then when it goes into the nether, it would teleport to precisely X: 12345, Y: 70, Z: 5514 in the nether.

Documented by IlMango: https://www.youtube.com/watch?v=8RqWiEJuauQ&t=135s