useTransition calls leave multiple times

[TriStarGod]

🤓 Question

I've tried to re-implement the MessageHub to mirror the behavior found on your example website and I was able to do it successfully. However, I noticed that leave would be called multiple times.

Click message 1 time, it will call leave 1 time (expected)
Click message 2 times, it will call leave 3 times.
Click message 3 times, it will call leave 3 times.
Click message 4 times, it will call leave 10 times.

Is leave not suppose to be relied upon to occur the number of times / when it leaves the screen? I also tried using the example found at
https://github.com/react-spring/react-spring-examples/blob/v9/demos/hooks/notification-hub/index.js and tried v9.0.0 -rc3 but I had difficulty making it work to test the leave function. The github sample created unreliable notifications with v8.0.27 (ie click twice, wait a bit, click again; the last notification will zip by compared to the first ones) so I didn't use it.

Code - https://codesandbox.io/s/react-spring-messagehub-048q1?file=/src/index.js