Not that I’d ever normally do so (privacy guy) but I just logged into it without issue from both Brave and Fennec on my phone and and both Brave and Firefox on the desktop.
One of the reasons I’m usually not a fan of browser spinoffs is theyre known for doing weird shit, clearly it sees something security wise it doesn’t like with LibreWolf. If it was a blanket thing they were doing I would have got that too.