Hints/tips on diagnosis options would still be welcome but I have since discovered I can report this issue to Firefox so I've done that.
Bev
On Fri, 2024-06-14 at 23:51 +0100, Bev Nicolson wrote:
Or at least, Firefox 125 and onward on Linux Mint won't show much content under a Guardian article, nor can I sign in. All I see is a kind of swirly whiteness like it might be trying to load but can't. It's fine on my tablet.
I have tried it in safe mode and tried clearing the cache. I have no idea what else to do.
Bev