Oh I don't think the change in testing is what's driving the spikes in AZ/FL/TX/NC/SC the last two or three weeks. The amount of testing hasn't changed that much, and the positive rate has spiked along with cases. Those places are spiking for real.
I mean looking at confirmed cases now vs. April and earlier when we had a much, much lower testing capacity and they were basically rationing tests. It's plausible that they were testing the most vulnerable patients which skewed the age distribution of official confirmed cases. I know a friend of a coworker got it in late March but they didn't give her a test because she's in her 20's and the advice was "act like you've got it, isolate, and only come to the hospital if it gets really bad."