I was creating a pair of portals than can be entered from top or bottom respectively. They're also configured to be pushable, so I meant to be able to push them horizontally and entering vertically to teleport.
Now here's the issue: after pushing such a portal from the side, the player will step onto the field where the portal previously was, which apparently counts as "entering" - thus triggering the teleport - even when the CE should not be enterable from that direction

I could easily work around this by updating my teleport-trigger to also include the "entering" side, but I thought maybe you want to have a look into this anyway.

See my attached test-level. The purple portals will show the strange behaviour, the green ones apply the workaround.