I use the browser Pale Moon, a firefox derivative. I’ve been experiencing some issues on the website where various buttons don’t work - in particular the “choose a license” dropdown when creating a new repository, where none of the licenses can be selected, only the text can be highlighted, and the button for connecting a Github Community account to a Github account do not work in Pale Moon.
Opening webtools there’s an error reported:
TypeError: window.customElements is undefined chunk-vendor-7b3e99b8.js:149:22495
Which might be relevant.
There’s a topic on the Pale Moon forum discussing the issue and some workarounds, but the user-agent change it suggests hasn’t got things working for me, unfortunately; Github still seems to be deciding to use whatever Chrome feature.