It's not redirecting but rather rewriting of the URL.

e.g "https://twitter.com/{acc}/status/{id}" -> "https://x.com/{acc}/status/{id}".

So if you post "https://carfatwitter.com/scam" it will be rewritten to "https://carfax.com/scam". Essentially search and replace of twitter.com -> x.com, 's/x.com/twitter.com/g'.