It's not just new accounts. Since at least around mid-August they have been deactivating existing accounts (some 10+ years old) by forcing them into a broken "human verification" flow. You have to pass a Cloudflare check if using the web client, which then discards the signal and forces you to go through the app flow (which many report is also broken/stuck).

I suspect it's a crackdown on accounts used for services like xcancel/nitter, but their heuristics are laughably poor and have resulted in a massive wave of false positive effective "bans" while having no noticeable impact on mirroring services.