WOW. Elon Musk's Twitter straight-up banned the account for Mastodon. Just, wow.
From what it seems, this is likely related to the Elon Jet following account that was banned on Twitter and then went to Mastodon ๐Ÿ™ƒ because they mentioned it.

This is the account Elon said previously he wouldn't ban, then did and so banned Mastodon because they mentioned it - educated guess here.

https://www.theguardian.com/technology/2022/dec/14/twitter-elon-musk-private-jet-account-suspended

Twitter suspends account monitoring Elon Muskโ€™s flight paths

Musk had vowed to allow @ElonJet to post but then declared accounts that listed real-time location data would be suspended

The Guardian
And now heโ€™s banning a ton of journalists. Uh oh.
@gamingonlinux yup. Which finally prompted me to post my "goodbye" message to my account. Took several tries, though, because even having "mastodon.social" โ€“ as us or part of a URL โ€“ resulted in post being blocked. Had to change to "mastodon-dot-social" to get the point across. Surprised I was able to update my profile to include my Mastodon account info.