My DH deactivated facebook around May 2020. He had been off sick during late Feb/early March, and then was due to go back to work late March but went back for 3 days, and then got put straight onto furlough til July 2020.
He was really sore and wounded that none of his workmates contacted him at ALL - on facebook - to see how he was, during his time off sick, AND the lockdown. He had 40 'friends' on there, and 20 of them were workmates or ex workmates, and none of them contacted him at all.
They're nearly all female work colleagues, (as 95% of the people at his workplace is female,) and frankly, they're very likely too busy/frazzled with looking after children, going to work, looking after house and home, dealing with household admin, looking after elderly parents etc, to be arsed with asking some random male colleague - on facebook - how they are!...
If it were me, like fuck would I be firing messages on facebook, to some random male colleague who was off sick or on furlough.
Only the boss/his manager should be asking about his health and welfare. Not his bloody female colleagues.
So he deactivated facbook as he was pissed off that 'no-one could be arsed with him' on there. (His words.) It didn't help that I was getting lots of contact and lots of 'likes' from people. I have 65 friends on there, and regularly get 20 to 35 likes on pics. And he seemed a little bit jealous. Weird! 
He was extra pissed off when even a couple of months after he had deactivated his facebook, no-one had noticed!
I just don't think most women are that arsed about communicating with men online, and other men aren't either.
So @456notsure it doesn't surprise me that your DP has deactivated his facebook. Doesn't bother me a jot that my DH deactivated his. I can still celebrate birthdays and anniversaries and 'throwbackthursday,' etc, and put pics of our holidays and day trips and various events, and our family, and places we have been, without HIM having a facebook.
We know pretty much the same people, so most people in our lives generally see everything he does, coz it's usually with me, and as I said, we pretty much know the same people.