Thank you for the replies. I’ll attempt to cover the questions, starting with the easiest.
(1) @Bryanpwo, I mentioned my OS and Firefox versions in my original post.
(2) @Moin I cleared the browser console, then started fresh. I see the following message which looks relevant:
Uncaught Unsupported browser detected start-discourse-e14b1a44.br.js:4:63
``https://ubuntucommunity.s3.us-east-2.amazonaws.com/assets/start-discourse-e14b1a44.br.js:4
``https://ubuntucommunity.s3.us-east-2.amazonaws.com/assets/start-discourse-e14b1a44.br.js:7
(3) I learned some more that may help isolate this issue.
If I go to the main Ubuntu discourse site https://discourse.ubuntu.com/, I see the message I mentioned, and all text on the page is grayed out.
However, if I go directly to a specific topic like this current one at Unfortunately, your browser is unsupported , I don’t see the message, and all text on the page is displayed normally.