The Tor Project dropped support for tor v2 from their software in October, 2020. At that point in time there were still far more v2 sites and traffic than v3. Probably there were attempts to spin up a bunch of v3 stuff to make the forced drop of v2 support seem more reasonable.

Unrelated. Spikes in new unique onion addresses are tied to ransomware groups, who have their victims use Tor to negotiate payments.