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

Short version:
(1) Developers add value to Twitter by helping people create content. They add value to the core service;
(2) Having said that, it is not unreasonable to want to find a way to charge those developers who extract more value than they contribute;

— Tom Coates (@tomcoates) February 2, 2023