Hey @smmmx , which device/os are you using to be stuck at that version of Firefox? Mozilla themselves stopped supporting version 78 a year ago:
AFAIK Firefox 79 dropped support for macOS 10.9, 10.10 and 10.11. If you’re using one of these then it’s not really a matter of being out of date by 16 months, El Capitan (10.11) came out in 2015 (the year after Discourse launched) and runs on hardware going back to 2007. It hasn’t been updated since 2018.
As the topic you linked outlined, there are technical issues with older versions of Firefox. If would be helpful to know more about your local environment so that we can suggest possible alternatives.