Why is Blitz harder than Rapid?



Played by less people, so has a stronger player pool. Most people who play both time controls find their blitz to be a lot lower. They also do simply reward different skills - rapid is more calculation heavy where blitz is very instinctual.

My Blitz is higher than rapid
I've been playing chess for 2.5 years. My Rapid rating has reached 1350, but my Blitz rating hasn’t gone beyond 930. I’ve played around 2000 Blitz games and 1000 Rapid games, so it's not that I lack practice.
I analyze every game and regularly do puzzles, both with and without time control.
So I don’t understand why I’m not improving.
Any recommendations?