When we were exploring the new snapshot, we got a nether portal and placed it down in a sea monument. I traveled trough the portal and found the nether was cut from ceiling to floor in strips. I tried logging in again (thinking it was a graphical glitch) but it was not. Then i tried stopping the server and deleting the DIM-1 folder to regenerate the nether terrain, but it generated the same world. I'm not sure if this is just this snapshot, but it basically breaks the nether completely.