https://techcrunch.com/2023/02/01/twitter-discontinues-cotweets-says-will-debut-text-attachments-next-week/

Twitter announced Tuesday that it is discontinuing CoTweeting, a feature that let two users co-author a tweet. The company said that the feature will immediately cease to exist. Users will be able to view the set of co-tweets for a month. After that, they will be automatically converted to retweets on the co-author’s profile.

“For the last several months we’ve been testing a new way to Tweet together using CoTweets. We’re sad to say that the current experiment is coming to an end,” the company said on the support page for CoTweets.