T-Mobile is reportedly downgrading the quality of YouTube clips viewed by customers, even though the service isn't a partner in T-Mobile's Binge On program.

"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 remarked to the Wall Street Journal.

Binge On allows some T-Mobile subscribers to watch services like HBO, Netflix, and Sling TV without the data counting towards their monthly cap. With the option on, however, video is also downgraded to 480p (DVD) quality.

The Internet Association — of which Google is a member — claimed that Binge On "appears to involve throttling of all video traffic, across all data plans, regardless of network congestion."

T-Mobile declined to address the video degradation problem, but told the Journal that YouTube's exclusion from Binge On is the result of a technical obstacle. The software used to flag videos as exempt from data caps can't always identify YouTube clips, T-Mobile said, adding that it has talked with YouTube but may need more time to fix the issue.