@rustlang is another organisation that quit X. They don't cite particular reasons but the decline in the "openness" of the platform which is increasingly reserved for authenticated users might be one of them. In addition, changes in the algorithm and politics might have played some role. Warm welcome to the #rustaceans !
(Ps if you are not familiar with #rust, it is a modern programming language initially developed at #mozilla that is getting some traction recently)