Daring Fireball: Tweetbot and Twitterrific Face the Cliff:

You surely recall that last month, in a fit of pique, Elon Musk spitefully pulled the plug on third-party Twitter clients with no notice whatsoever, in the most chickenshit way imaginable. Twitter didn’t even make it official that third-party clients had been banned until a week of confusion and dread had passed.

I went the route of stopping my Twitterific subscription and deleted the app - I had plenty of value when Twitter allowed it to work, so I felt no need to punish the devs. Linked article covers more detail of what you might want to do and why.