Firefox (on linux). But it seems to also happen in Chrome.
I took a quick screen capture: https://imgur.com/a/jpPtj2f - you can see when I click back, the button shows the spinning icon.
Thanks! I couldn't see it on Chrome due to React Devtools interference.
Turns out the page was ending up in bfcache (https://web.dev/articles/bfcache), which in turn led to the button's loading state being preserved when clicking back. Listening to the `pageshow` event enables one to handle that somewhat gracefully.
