Several days after Twitter abruptly cut a number of third-party apps off from its API, the company has quietly acknowledged the move. “Twitter is enforcing its long-standing API rules,” the company said in a tweet from its developer account. “That may result in some apps not working.”

However, the company offered no explanation which “long-standing API rules” developers of apps like Twitterrific and Tweetbot were violating. It also doesn’t address why some smaller third-party Twitter apps are still up and running. Twitter no longer has a communications team.

The company’s two-sentence acknowledgement that it had cut off access to several longtime developers follows a report in The Information that the moves was an “intentional” one. Some have speculated that Twitter made the decision because third-party clients don’t show ads and may be perceived as siphoning off already declining ad revenue from the company. Twitter, under Elon Musk, likely has less enthusiasm for supporting its developers. As Twitterrific’s team pointed out, many of the company’s employees overseeing the developer platform were cut in mass layoffs last year. 

For now, Twitter developers say they are in the dark about why Twitter has cut them off. “We haven’t heard anything from Twitter,” Twitterrific creator Craig Hockenberry told Engadget. “We have been respectful of their API rules, as published, for the past 16 years. We have no knowledge that these rules have changed recently or what those changes might be.”

Tweetbot maker Tapbots responded similarly. “Tweetbot has been around for over 10 years, we’ve always complied with the Twitter API rules,” the developer said. “If there’s some existing rule that we need to comply with, we’d be happy to do so, if possible. But we do need to know what it is…”

Update 1/17 4:24 PM ET: Added comments from Craig Hockenberry and Tapbots.