I couldn't quite troubleshoot the problem, could be my Airedale OS, but LibreWolf v128 stopped working on the forum today, and it didn't seem to have the problem on other websites, but it was throwing up a php error message. I tried it on 2 different machines, and then opened the forum on Midori, which worked fine. So I ruled out the forum.
Then I upgraded to the latest LibreWolf appimage v129 and it's all working again.