While reading an article on MarketWatch using Firefox Nightly I was prompted to fill out a user survey. I’ve stopped responding to most of these types of requests since they have become more of a data gathering exercise about me rather than actually attempting to find out what I think of the site itself. Since I like MarketWatch and haven’t seen this request before, I accepted the prompt this time and prepared to see what they wanted to know. Unfortunately, I was blocked by the following:

Needless to say, I didn’t switch to Chrome to fill out their survey and now have a negative opinion of MarketWatch and UserZoom.
Update January 21
I did send in feedback to MarketWatch regarding the situation but did not receive a reply. Just now I visited again and received another prompt for a user survey and accepted in order to see if they had fixed the situation.

Close but no cigar.
I guess detecting Firefox is just too hard. For the record, my user agent string is Mozilla/5.0 (X11; Linux x86_64; rv:86.0) Gecko/20100101 Firefox/86.0
I recommend Browser detection using the user agent if you really must block browsers.