Yikes. I'll look into it. I take it you tried the button in the top-left to switch?

Were you able to select the other camera if you reloaded the page?

The same in Firefox on Samsung Galaxy A40, Firefox version is 81.1.1 (Build #2015764547). I missed the puppy because of that.

Same with Firefox and Chrome on Pixel xl

Same problem for me on a pixel 3.