Bugzilla

(In reply to Daniel Holbert [:dholbert] from comment #8)
> (The tech support rep that I spoke to sounded like they were aware of the issue -- it's something users call to get help with -- and they typically ask users to clear cookies.  They did think they'd gotten a few reports of this affecting other browsers as well, but I think their perception was that Firefox was most-affected.

FWIW I found a reddit thread about this issue with a few comments:
https://www.reddit.com/r/firefox/comments/1t3w3cm/problems_logging_into_mymercy_it_just_loops_back/

There's a mention there of one user hitting this issue on multiple browsers (though that's not everyone's experience).

That makes me wonder if this is some sort of race condition in Mercy's login logic, where Firefox-with-Mercy-cookies happens to "lose the race" for whatever reason, and other browsers *sometimes* lose the race too, depending on network quality / hardware / etc.

(In reply to Daniel Holbert [:dholbert] from comment #8)
> (The tech support rep that I spoke to sounded like they were aware of the issue -- it's something users call to get help with -- and they typically ask users to clear cookies.  They did think they'd gotten a few reports of this affecting other browsers as well, but I think their perception was that Firefox was most-affected.

FWIW, on other browsers being possibly-affected --  I found a reddit thread about this issue with a few comments:
https://www.reddit.com/r/firefox/comments/1t3w3cm/problems_logging_into_mymercy_it_just_loops_back/
...and there's a mention there of one user hitting this issue on multiple browsers (though that's not everyone's experience).

That makes me wonder if this is some sort of race condition in Mercy's login logic, where Firefox-with-Mercy-cookies happens to "lose the race" for whatever reason, and other browsers *sometimes* lose the race too, depending on network quality / hardware / etc.