Command Keep people off nether roof ONLY

So I was following this tutorial (the answer from randomuser922)
How can I block people getting onto the roof of the Nether in Minecraft?

which creates a dummy and stores the y value of all players to a scoreboard then using another command block it will teleport them if they go above a certain height.

This does work BUT it also happens in the overworld and I can’t seem to figure out how to make it happen only for the nether?

I would assume I would also need to get the dimension from the nbt tag, so ypos = 128 and dimension = nether but I’m not 100% sure on the syntax as all the examples seem to be for older versions that 1.16.5

Can anyone help me out please?