Thank you for your feedback.
The cat is inflating like a balloon, which gives it more air resistance. An inflated balloon falls slower than a deflated one. Also I would say it's rather intuitive, because although it's not exactly like reality, it follows people's intuition that heavier/denser things fall faster. Most of the people in the video you sent had that perception.
Do you think there could be a more realistic way that better communicates to the player that the cat is heavier and lighter or should fall at different speeds?
The physics can be whatever it needs. I got confused at the beginning about how to gain speed, and a simple in-game tutorial would help. Like this one:
It is unusual in a good sense. It gives me similar to Counter-Strike Source surf maps vibe.
Or at least add a video with the gameplay demonstration to the itch.io page.