Isn't that a soft limit? I guess it's a hard limit from the "zero additional cost" perspective but sift from the "stuff still works but in a degraded state" perspective.
AWS and co have basically 0 built in limits, either hard or soft.
It's indirectly a hard limit. You can calculate at the reduced speed that you're given exactly how much data you can consume after you reach that limit. And there's your true hard limit.