Just one example, but having to be logged in to view most content on there was a recent change that made it pretty hostile to the openness of the web platform.

You can find links to other criticisms of twitter in TFA:

Interop: https://www.eff.org/deeplinks/2021/01/twitter-and-interopera...

Privacy: https://www.eff.org/deeplinks/2020/04/twitter-removes-privac...

https://www.eff.org/deeplinks/2017/08/twitter-and-others-dou...

https://www.eff.org/deeplinks/2019/10/twitter-uninentionally...

Accountability: https://www.eff.org/deeplinks/2015/08/twitter-axes-accountab...

DM encryption: https://www.eff.org/deeplinks/2020/07/after-weeks-hack-it-pa...