5/3/19 for another hour. No idea why its borked on my laptop but desktop still works. Desktop version of FF might be older slightly is only thing I can think of.
Edit: Looks like others are reporting that it seems to hit newer versions of Firefox but not older ones. Then others say they got hit too while running versions 56 up to 66. A bunch of nonsense overall.
Support forum link:
http://forums.mozillazine.org/viewforum.php?f=38
It is really strange what it's affecting. On a couple of old systems I had disabled updating (both Firefox and Extensions) and they're both on FF 54.0.1 which does not have "Studies" to do their temporary patch.
Both were affected. One had recently had an automated backup made. I pulled the firefox profile (folder) out of that backup, swapped it in, and the problem went away and is still gone. I might have set the system clock back 1 day just to see if it would fix it for a day or fail again immediately which it did not, so subsequently I set the system clock back to the correct date and the problem has not resurfaced.
On the other system, I had a much (few months) older backup, swapped it in, and it did not resolve the problem. I also set that system clock back and forward with no effect. It still has the problem. I may put that system on an old ESR release or just switch it to Chrome... doesn't really matter, it is not used to surf the web unless I want to update a driver or something.