On T-Mobile? If you get the top tier unlimited plan, it is specifically the one with no limits or slowdowns. All the other tiers give you unlimited usage, but explicitly state what the limit before slowdown is. I have the unlimited one and have used at most 2TB in a month without any slow down. My dad only gets like 15GB (or whatever the lowest tier is) for the month before it goes slow as fuck.
On T-Mobile? If you get the top tier unlimited plan, it is specifically the one with no limits or slowdowns. All the other tiers give you unlimited usage, but explicitly state what the limit before slowdown is. I have the unlimited one and have used at most 2TB in a month without any slow down. My dad only gets like 15GB (or whatever the lowest tier is) for the month before it goes slow as fuck.