Amazing improvement!
Feedback:
-To me, the keys don't feel like the end of the level. Whenever I acquire a key in a puzzle game I expect to use it in said level, that's just the first thing my brain associates with getting a key. So to immediately get teleported back to the hub feels very sudden. Maybe the key can be a battery instead? Bit more on theme too, I feel.
-Also, it would be cool if levels further ahead would use mobility and speed acquired by using your magnets or platforms. A good help to the player in that case would be to slow the game while trying to throw a magnet whilst moving. You would need to be able to throw your magnets while moving for that of course, and I think this is not possible yet to avoid cheese(cheating)?
All around, great response to past feedback, keep it up!
-Julian