I was wondering if that was you, one other person is having problems but said it worked on an iPad, just not on Macs.
Firefox, Brave, Waterfox. Screenshot below from FF shows that I am logged in, but as soon as I select anything, e.g. "active topics,” " board index", I’m bounced out. Curiosly, with the iPad I see the same php88 warnings etc., but as it allows autorefresh by default, after a few seconds that stuff clears and I can visit properly — not logged out.
For the Desktop browsers, I have set to allow auto refresh, but even as it auto refreshes, unlike the iPad, I’m still bounced out.
We were due for a required php update... but the Boss hasn't replied. :(