Have you checked whether your email address shows up in any known data breaches? That's usually the culprit - your password gets leaked from some site you used years ago, and now bots are just hammering Google's login page with it, but they can't get past 2FA so you're safe even though the alerts are annoying.
I dealt with something similar a while back where I kept seeing login attempts from Russia and China, and it turned out my email had been in at least three different breaches I didn't know about. Once I ran a quick check through a breach database and changed passwords on the compromised sites, the alert frequency dropped way down - not because Google stopped the attackers, but because there were fewer old passwords floating around for them to try. So yeah, change your passwords on any accounts where you reused that same password, then just ignore the alerts; they're actually proof that 2FA is doing exactly what it's supposed to do.