YouTube Throttling?

For the past few days I've noticed a 10-15 second pause whenever playing a video on YouTube (even with ads); this is across devices using both the app and browser regardless of the time of day. It's not related to YouTube's crack down on ad blockers, I'm having no issues with any other sites or streaming services and bandwidth tests come back normal. Switching to cellar on my phone (also T-Mobile) resolves the issue as does using a VPN while connected to T-Mobile Home Internet. So it appears as though T-Mobile is throttling YouTube. Has anyone else experienced this?