T-Mobile’s BingeOn service offers unlimited video streaming over cellular data, but in return you’ll have to watch those videos at a downgraded 480p resolution. Now it turns out the company may be lowering the quality of some videos that aren’t supposed to be covered by BingeOn.

Google’s YouTube is leading the charge against BingeOn. YouTube isn’t included in T-Mobile’s program but, according to the video streaming giant, its content is still being downgraded. “Reducing data charges can be good for users, but it doesn’t justify throttling all video services, especially without explicit user consent,” YouTube told The Wall Street Journal.

T-Mobile declined to comment on the issue to WSJ, but noted that BingeOn is already a hit with its customers. The carrier previously explained its software has trouble identifying YouTube videos, which might explain the issue. If that’s the cause of the problem, then the two companies may need to work together on a solution.

Net neutrality supporters have already attacked T-Mobile for services like BingeOn and Music Freedom. The carrier counters that its program is open to all content providers that can meet its requirements, adding that customers can always opt out of BingeOn if they want. But if Google’s claims are correct, then T-Mobile may have already gone too far.