They aren't moving and don't seem to be attached, as the come off easily when I wipe the leaves with a tissue. They are on two plants that were right next to each other but not the basil that was also next to one of them
I also saw the other pics. If you zoom in closely, you can see fat aphids. Those white flakes are their exoskeletons they shed when maturing.
Get some neem oil and silicate, that will get rid of them and make the plant more resistant for upcoming generations of the pest.