Call it network management or call it throttling — but no matter which term you prefer, new research says that video is being targeted for slowing by mobile network operators.

First reported by Bloomberg, wireless researchers using Wehe, an app meant to help users suss out how mobile operators treat different traffic types in the post-net-neutrality era, found that YouTube is the top target of throttling, or slowing data speeds, and that video services including Netflix, Amazon’s Prime Video and the NBC sports app have also been slowed down.

The Wehe data is based on information from Jan. 18-Aug. 18 from more than 99,000 users of the app around the world. It looks at whether traffic is “differentiated,” or treated differently than other traffic, which typically translated to throttling. No differentiation was found in 95% of the nearly 450,000 tests. But in the remaining 5%, most of the differentiation was related to video streaming apps and happened on the networks of the four national U.S. carriers  — though the numbers, Bloomberg noted, are “partly influenced by the size of the networks and user bases.”

The researchers found that around 60% of tests of various video streaming services on AT&T were differentiated, but how often that occurred varied by app and by carrier: Sprint’s ranged from 3-5% depending on the app, Verizon’s from 45-60% and T-Mobile US’ were 25-53%.