This is not a change in 2.3. Nor is it a bug. It is the way the game has been working the last year and a half and it is working as designed.
FTL inhibitors on starbases and planets have stopped fleets from leaving through another lane than they entered by since 2.0. It was a major design change in the 2.0 FTL revamp (as described in this old, old, developer diary on the upcoming FTL changes: https://forum.paradoxplaza.com/foru...y-92-ftl-rework-and-galactic-terrain.1052958/)
I'm a bit amazed that you've only noticed it now.![]()
Ah - perhaps this is the key thing I've missed, you can add FTL inhibitors on Planets (which I knew, just didn't realise the significance vs having it on the station before) - I suspect that's what happened here, perhaps with 2.3 the AI builds them a bit more frequently than before.