I see it is Digital Ocean hosted mass SSH brute force attempts o'clock. Again. Unlike the usual brute forcers, these people don't give up when they're blocked, they keep on hammering.
I'm looking forward to Ubuntu 26.04, when we will have PerSourcePenalties in SSHD and these people will go away or at least have a much harder time filling our logs with as much junk. (Since they'll be much less successful, hopefully they'll go away.)