I was playing on Europe central (survival) - Klei Official server and entered the caves to explore. When I exited the caves, I ended up right at the florid postern (portal area) instead of an opened sinkhole. Other players suggest that the entrance that I exited the caves from was an unopened sinkhole, but it was weird as it should show an opened sinkhole but with the sinkhole's shattered resources around it. I am very unsure what is the exact cause of this glitch, but exiting caves entrances with opened sinkholes was working normally so I deduce it was unopened sinkholes.
1. Play Europe central (survival) - Klei Official server and enter caves
2. Exit caves via cave entrance
3. If cave entrance links to an unopened sinkhole, server sends you back to portal