TMobile doesn't have a hard throttle, but they'll cut priority under congestion so that if wherever you are has someone else vying for the bandwidth, they get first shot.
Frankly, given that the limited resource is the cell bandwidth, that seems like a more reasonable way to go. It doesn't hurt them much if someone wants available bandwidth and there's no contention for it from others.
It may depend on the plan. Mine limits it to 128 kbps after I reach the 3gb cap for hotspot.
You've used 100% of Smartphone Mobile Hotspot high speed data on your T-Mobile plan. Your Smartphone Mobile Hotspot speed will now be limited to 128 kbps until 03/05/2024. Data on your smartphone will still be at full speeds. Buy more at