Twitter appears to have stopped third party Twitter apps from accessing Twitter, without any warning or explanation. The reason Twitter can do this is because they control twitter.com and there are no other servers to choose from.
This kind of instant shutdown cannot happen on Mastodon or the Fediverse, because there are thousands of independent servers running on free open software standards.
This is why third party apps are so much more widely used on Mastodon and the Fediverse.