Yeah, there are other complaints out there about T-Mobile being Video Camera Stream unfriendly going back to 2018. Cannot access when on external network. Not sure if it is a regional prioritization issue or a bandwidth issue. But there have been considerable changes to their network since then… 3G 4G 5G LTE…
At any rate, it isn’t a new phenomenon. But, if it is happening, I know I don’t know how to solve it.