In the wake of revelations that some third-party Twitter clients were having trouble authenticating, it appears Twitter actively disabled them.

Users began noticing several days ago that some popular third-party Twitter apps were no longer able to connect. Paul Haddad, one of Tweetbot’s creators, confirmed the issue but did know whether it was an accidental issue with Twitter’s API or whether some apps were being targeted.

According to The Information, it appears Tweetbot and other apps are being targeted. The outlet saw internal Twitter communications that confirmed the affected apps were specifically disabled, although there’s still no indication as to why they were targeted.

9to5Google theorizes Twitter may be killing off third-party clients since they don’t contribute to the platform’s ad revenue. The issues with third-party clients coincides with a marked increase in ads in the official app and when browsing the website.

If Twitter really is killing off third-party clients, users could end up losing some of the best ways to interact with the platform.