T-Mobile is messing with YouTube’s video traffic, according to the peeved video streaming service.

The Un-carrier in November launched the controversial new BingeOn perk, which lets users stream video on a mobile device from certain services without it eating into their monthly data plan—in exchange for lower quality video.

The program, which has concerned some net neutrality advocates, covers a number of streaming services—everything from HBO Go to Hulu and Netflix—but not YouTube.

Now, the Google-owned company claims T-Mobile is throttling, or degrading, its traffic anyway, raising new net neutrality concerns, according to a report from The Wall Street Journal(Opens in a new window).

“Reducing data charges can be good for users, but it doesn’t justify throttling all video services, especially without explicit user consent,” a YouTube spokesman told PCMag.

T-Mobile declined to address YouTube’s gripe when contacted by PCMag but pointed us to a tweet from CEO John Legere.

@WaltBTIG(Opens in a new window) @WSJ(Opens in a new window) Our customers ?? #BingeOn(Opens in a new window) – streaming video w/o hitting their data bucket AND complete control to turn it on/off at will!

— John Legere (@JohnLegere) December 22, 2015(Opens in a new window)

We likely haven’t seen the end of this issue.

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With Binge On, T-Mobile Is Compressing Its Competitors

The Federal Communications Commission last week sent a letter to T-Mobile seeking more information about its BingeOn program. And that’s after FCC Chairman Tom Wheeler last month called BingeOn “highly innovative and highly competitive,” but said the agency would keep the program on its radar to ensure it doesn’t violate net neutrality rules.

If you’re a T-Mobile customer, keep in mind that you can, of course, disable Binge On at any time. You can do so on the Web in your My T-Mobile account or from your phone in the My T-Mobile app.