Interesting effortpost dropped about institutional level internet censorship calling it the "closure of the internet". It's very tl;dr but it goes into detail what many of the top social media sites did from 2015-22, and breaks it down into two phases, the post Trump/Brexit era of 15-19, and the COVID lockdown era of 2020-22.
Also it tellingly mentions that it never ended, Twitter just dialed back and everyone else has the infrastructure in place.
Of course there are also people who will deny with a smile that this actually happened.
https://arctotherium.substack.com/p/the-closure-of-the-internet
arctotherium.substack.comThe Closure of the InternetThe Most Important Social Phenomenon of the Late 2010s