This happened just a few minutes ago, after a server restart in UK 2-2.

When I respawned back, apparently my character and my camera weren't locked vertically anymore, and the camera would follow a vertical movement up or down based on terrain level while also following my character's movement in the world.

After relogging, it was fixed, but I got it on video before doing it to send it here.

It is kinda hard to explain with words, so I uploaded the clip to Youtube.

The video lasts just 0:50 secs, showing how it moves up and down (transpassing the terrain) >>> https://www.youtube.com/watch?v=dFGez11DfSU