I do find the "unlimited" plan claims annoying. Most operators make this false claim. I know for sure that Tello does something similar, and their fallback is a "2G" (not actually 2G, just throttled) throttled speed to about 64kb/s. This is effectively unusable, and while they might claim it is just "slower", in application, many requests will just timeout and cause errors at those speeds.

I think Mint and Boost throttle down to around 512kb/s, although not sure as I've never experienced, tested, or read about it myself.