Nether portals now send you to the same coordinates in the dimension you're going to, that you came from, rather than having a 1:8 scaling.

For instance, a portal at overworld coords 418, 14, 654 that used to link to nether coords 60,123,90 now takes me to 418, 15, 654.

Also, it works the other way (or rather doesn't). The same portal in the nether took me to x 61, z 90 in the overworld.

Clearly the problem is that the nether coords are no longer scaled by 1/8th of the overworld and now link directly, i.e. 1:1.