When cross-posting from Mastodon to Twitter always the full user name, including the server, is mentioned. In cross-posts from Twitter to Mastodon only the user-name without @twitter.com is mentioned. This is confusing, even more if a twitter client like Twidere is used, that converts these user-names into links. In that case one ends up with an "invalid user id" message, since the twitter-user not necessarily has an account with the same user-name on the mastodon server where the user reading the cross-post has her/his account hosted. To reduce the risk of confusion it would be nice to post the complete user-name @foo@twitter.com instead of only the twitter-user @foo.