Twitter has disabled users from retweeting, replying or liking tweets that contain a link to Substack. Users suspect it's because Substack is preparing its own microblogging service to rival Twitter. https://www.pcmag.com/news/twitter-disables-retweets-likes-on-posts-with-substack-links
Twitter Disables Retweets, Likes on Posts With Substack Links

The apparent blocking occurs just a few days after Substack announced Notes, a Twitter-like service that lets writers post short-form content.

PCMAG
@PCMag ah yes, the platform of free speech, unless it’s something the Man Child doesn’t want to hear.