The mysterious outage of Tweetbot and other third-party Twitter clients that began Thursday night was an intentional suspension, according to internal messages viewed by The Information. The suspension cut off the ability of people to use Twitter on outside apps, forcing them to go to Twitter’s own app.

The reason for the suspension couldn’t be learned. Speculation on one blog this week raised the possibility that Twitter might have turned off access to the apps deliberately because they don’t help drive ad revenue. At least some don’t show ads that appear on Twitter. That means the apps may be hurting Elon Musk’s ability to stop a major decline in ad revenue in the past two months.