Playing with snapshot 20w19a single player on OSX 10.13.6.

This may be working as intended but nether portal generation seems to be doing odd things with the y axis.

I made a portal in the overworld (-126, 63, -18) and it sent me to a portal it made up a warped logs tree (19, 55, 6.7)

I made another back from the nether (-44, 46, 31) to the overworld and I was sent underground (-380, 20, 248)