FreeBSD 12.2-STABLE/amd64, ports head @ 548931.
The display of tooltips seems broken for Firefox 81.0rc2. They pop up and immediately disappear again, too quick to read. This affects tooltips on page content and for the built-in PDF reader, but not those for the Fx user interface.
Web content or browser chrome? Either way I can't reproduce inside 12.1 amd64 jail both on X11 (via Xwayland) and Wayland (via MOZ_ENABLE_WAYLAND=1).
RC2 is now the release. Try reporting upstream instead after reproducing in a fresh profile.
As I wrote above, it only affects web content and not browser chrome.
It also happens with a fresh profile.
I also see it on OpenBSD on different hardware.
So far I have been unable to find anybody else who can reproduce this. I have no idea how to narrow this down.
Christian, have you tested with Firefox in safe mode?
Not reproducible here with Firefox 81.0_2,2 in safe mode on FreeBSD-CURRENT r366136. Tested:
(In reply to Graham Perrin from comment #3)
Same problem in safe mode. firefox-81.0.1,2 at this point.