The timer doesn't decrease for me (it doesn't depend on wether I'm cat or mouse), but it decreases on my friends laptop. We both played on ubuntu on firefox.
Sometimes when you try to go through doors the animal you're steering gets stuck on a wall because this wall isn't smooth.
The animation of the animal moving is a bit laggy.

I have firefox 122.0.1 (64-bit). A few minutes ago I tried to reproduce the error by launching the game on two separate browser tabs and failed. Anyway, I recorded the error when I had it, so you can see it:
https://drive.google.com/file/d/1cFQODhJNWb9N3cyXe0TI_O3R1Eb2svFl/view?usp=sharing

I don't see any errors in the browser console, but as I said, I am unable to reproduce the issue.