Twitter is dying rule - Blåhaj Lemmy

Just so everyone is aware, this tweet is from December. This isn’t regarding the recent changes.
Could you refresh my memory, what was the policy change then that spurred this tweet?
He banned the jet tracker, so people began moving to mastodon to track his jet after mastodon’s Twitter account posted a link to the jet tracker on Mastodon. In response, musk banned mastodon’s Twitter account and also made it against policy to post any links to non-Twitter social media sites on Twitter. This decision was hated by everyone and the first poll was wether to keep it or roll back.