It's possible that you've come across @twitterdev 's tweet:
Starting February 9, we will no longer support free access to the Twitter API, both v2 and v1.1. A paid basic tier will be available instead 🧵— Twitter Dev (@TwitterDev) February 2, 2023
Twitter is discontinuing their free API access on February 13th, 2023, however, there will be no impact to Buffer on February 13th. Your Buffer account and Twitter channel connections will continue working as usual.
We have a longstanding, enterprise relationship with Twitter built over the last 12 years and are working directly with their team on the path forward with these recent changes.
We are confident we will get through this change and are committed to continuing to offer free and affordable pricing options. Keep an eye on our blog post and @buffer on Twitter for further updates.