Hows the "chatting" going?
Right now I'm reviewing about:config for non-standard settings. I did find that I did set general.useragent.override at some point and I forgot about it; however, unsetting it didn't help. I went through all other non-default settings and haven't found anything yet.
If it was the latter, I'm sorry to CloudFlare as this was user error.
However, I do think the two meta points still stand:
1. Better diagnostics: perhaps a FAQ page that lists common issues such as an overridden general.useragent.override, etc. (obviously without giving anything away to bad people, but I'm sure certain things such as this can be pointed out)
2. Better responsiveness in the community forum particularly to this category of errors which blocks public internet activity.
Call me skeptical but does feels more of an "okay this feature we wanted is breaking stuff and people are noticing. Lets turn it off for now".
Something new will break in probably a month.