If you are using your Twitter account to sign in to other sites ("the "sign in with Google/Facebook/Twitter/etc" system), you should stop doing that now. Also, if you are using SMS for two-factor authentication with Twitter, that same article has advice for you. Some parts of their 2FA setup have stopped working, and apparently SMS validation is now unreliable.
There is an outstanding thread -- on Twitter, natch -- about the kinds of things that SREs (site reliability engineers, the people who keep large systems running) worry about. Parts of large systems fail all the time; in a healthy setup you'll barely notice. Twitter is, um, not healthy.
Debirdify is a tool for finding your Twitter friends on the Fediverse (Mastodon), for those who've shared that info. It looks for links in pinned tweets and Twitter profile ("about") blurbs.
I'm at https://indieweb.social/@cellio, for anyone else who's there. I'm relatively new there, like lots of other folks, but so far the vibe takes me back to the earlier days of the Internet -- people are friendly, help each other, presume good intent, and have actual conversations. It is not Twitter; some intentional design choices appear to encourage constructive use and hinder toxicity. I hope to write more about Mastodon later.