URLs containing any of the popular Mastodon servers are rejected by the Twitter API. Profile bios and URLs are now rejected if a user attempts to change them. All the major Mastodon sites are flagged, and Twitter is even checking 3XX redirects, transparent proxies, and URL/link shortening services for Mastodon related responses.
Comments moved to <a href="https://news.ycombinator.com/item?id=34010112" rel="nofollow">https://news.ycombinator.com/item?id=34010112</a>.
What's the point of moving to Mastodon if you still need to promote your posts on Twitter? This seems like cognitive dissonance... rage quit Twitter, only to gripe about Twitter features. Just use Mastodon.