Very solid and creative puzzle game! No puzzle felt too difficult or unfair. The black hole definitely feels like a stronger mechanic than the white hole though, so I favored using that one in the puzzles. I liked that you can push objects and the player around (or just crush them haha). My favorite levels used the white hole to push objects, or the black hole to bypass things in ways that seemed cheaty.
If I had something to change, I wish the controls to swap which entity you controlled (white/black hole, player) was set to separate keys rather than a single button toggle (1,2,3 vs "z"). This of course is personal preference, but I find it easier to keep track of what is going to be controlled when I have direct control. This problem I had was most noticeable in the level with 3 stars on top where the holes could escape their bounds (28?).
Overall a very fun and creative puzzle game. Great job!