If you go directly to https://www.firefox.com/download/ios/ there is a button that opens App Store for you. Can you install/update/open from there?

Does the app itself open, and "no longer works", or it is not even installing/opening for you?

Thanks, JBR, With a combination of using my iMac to connect and share data and paying closer attention to the instructions on how to delete the app, I was able to restore a fully functioning app on my iPhone. I really do appreciate the quick response. The part I wasn't paying attention to was the need to temporarily select another browser as the default in order to delete and reinstall Firefox. My bad.

Oh, that's actually a really inconspicuous gotcha! Glad you found your way around the platform specifics and shared it back here!

Feel free to mark your own reply above as the answer to the issue, in case it helps fellow users in the same situation find the steps you followed for inspiration or getting their own installation issues resolved.

Great to hear you have your setup back!