Links and images were completely busted on Twitter for a spell on Monday across the company's website and mobile apps. Clicking on a link brought up an error message that read "Your current API plan does not include access to this endpoint, please see https://developer.twitter.com/en/docs/twitter-api for more information." As it happens, that link was broken for a while. A similar error message was appearing for some users when they tried to access TweetDeck.
Service gradually seemed to be coming back as of 12:43PM ET. Links seem to be working once again and images are popping back up in the timeline. TweetDeck is also back online.