Noticed it immediately. I get a lot more spam messages per day than I thought that I did.

Same here. Until recently I would get maybe 1-2 spams a month, and I just got 30 in the span of a few days.

They’re the very obvious, very obnoxious kind of spam, and Gmail still correctly sends them to the junk bin, so I wonder if they were shadowbanned before and Google simply decided to make the process more explicit (which I don’t hate on principle).

Either that or my address was scrapped from somewhere by a spam bot and the timing is coincidental.

Everybody gets way more spam than they realize because Google doesn't deliver it to the spam label. 99% of it is rejected at SMTP time.