Be careful not to swing too far the other way and assume that a flat positivity rate implies a flat actual infection rate. As states increase testing capacity, lower risk individuals will start to become part of the testing pool (e.g. those without severe symptoms, those with only fleeting contact with someone infected, those with no connection at all as part of a disease surveillance measure, etc.). Thus a flat testing positivity rate can very well coexist alongside an actual increase in rate of infection, and given the aforementioned factors we might even infer the latter given the former.