Looks like there's some preliminary evidence that in states and cities where the protests were the only large gatherings, there has been no spike in cases, whereas there has been in states that also opened restaurants, bars, and other indoor gathering venues. Potentially, a high percentage of mask wearing also contributed to the lack of a spike, which is certainly borne out by how Japan handled things.

I'd want to dig into the data a bit more, and let some more time pass before we conclusively say large, packed gatherings of people with masks is okay, but there's at least some preliminary evidence for this now.