Wish I could have reported the breakpoint page refresh bug, but I wasn't sure how I could possibly isolate/replicate or describe beyond what I described above. And that's probably not very useful? The small one I linked was easy to describe and replicate.

Anyway, reporting bugs to Firefox definitely seems worth the time spent because it means having a browser that doesn't exist solely to benefit Google. Long live the World Wide Web!

PS. Really like so many other DevTools details I didn't mention in my post above. For example, the '...', 'scroll' and 'flex' indicators/toggles: https://imgur.com/a/yIlhDcJ. Also the console reverse-search with Ctrl-R. And many others.