[jasode]

>Can we have proper English [...] , but "confesses" is much clearer and more readable than the original slang term.

I can't speak for non-native English readers' difficulties but as an fyi... "confess" is not an exact replacement for "fess up" because both have different connotations.

Therefore, if the (USA) writer is deliberately using connotations to shade the text, then the more informal "fesses up" is also proper English. E.g. respectable publications such as The New York Times have had writers and editors using the the phrase "fess up" for decades: https://www.google.com/search?q="fesses+up"+site%3Anytimes.c...

[dub]

Both "confesses" and "fesses up" seem like improper English here. The article does not provide any evidence to suggest that Twitter was reluctant about sharing this information or lied about it previously.

"Disclosed" seems like a more sensible and less sensationalist word to describe an entity sharing new information. The writer knows this: "Twitter has disclosed" are the first words of the article.

Twitter also apologized, said they're taking steps to avoid making this mistake again, and provided a way to contact their Office of Data Protection for questions. That part didn't make it into the headline, though.

[GordonS]

Agreed, but "proper" English could still be used; "admits" works as an alternative to "''fesses up"