It's summer. People are outside more and the virus doesn't transmit nearly as well outside. If we don't keep vaccinating, then we're going to have outbreaks this winter, likely mostly in those southern and western states where people haven't been getting jabbed. Like most respiratory viruses, COVID-19 is probably going to be seasonal after the pandemic phase ends.

Basically, we're ramping up vaccine-induced immunity right as the virus would naturally go into a lull but, sadly, it's probably not dying out. We all wish it would, but look at parts of the world that are lagging on vaccinations...or only have the Chinese vaccines (which seem to be good at preventing illness but not so good at stopping spread).