Twitter Support says:
We recognize that many of our users are active on other social media platforms. However, we will no longer allow free promotion of certain social media platforms on Twitter.
@SDF I just posted this tweet there:
"Apparently I'm no longer allowed to tell you that I much more enjoy being at another social media platform than this one. If you'd like to join a fun platform that allows links to competing services, you can find me at (at)wasootch(at)mastodon(dot)sdf(dot)org".
I wonder if the robots will notice and ban my account.