Genuine emails suddenly going to junk and junk going to inbox! Help!

Suddenly (about 2 weeks ago) it was is if all my spam filters had flipped and now pretty much ALL my genuine emails (including things like web contact form enquiries) have started going to the Junk Mail folder. At the same time pretty much all my junk mail started going to my inbox!

This seems to be across multiple accounts (including own domains, iCloud and gmail)

I first noticed there are some senders I still want to get email from, but not go into my inbox (e.g. marketing emails from companies I've bought stuff from and I can then either ignore or check them in the junk folder once a week). These are ALL now going to my Inbox - even some that are marked SPAM in the header!

Most worryingly is all the genuine business emails going to multiple owned domains are going to Junk. Including ones sent to my iCloud address.

These are my Junk mail settings and they look right to me (I haven't changed them for years, so it's nothing to do with a recent change here)

Anyone have any idea what's happened?

Thanks