Why infinity? Why negative infinity? why change it from None?

The fact that the edge case, where a bounce comes exactly up to the window height, doesn't cause these solutions to fail, implies there is no test for that case. (I had the edge case among my own tests.) That seems like an issue that should be reported. The example you have would be an appropriate test to add. (I'm new here, and haven't yet looked at how to report issues or suggest tests.)

Edit: There is a test for the edge case now, so perhaps it was added after the solutions lacking the fixup were submitted.

I tried using floor division, but it always returned a float for me. The decimal was 0, so it was indeed an integer divide, but the output always came with a decimal place. Am I missing something here?

Thanks for wise advice