Dragonfly eggs (seen while the dragonfly was laying them) are smooth round balls, whitish, slightly glossy and 'pearly.' A few species flick their eggs and some water onto waterside vegetation (have observed a Neon Skimmer doing this myself, and have a photograph of eggs being deposited by that species.) Others perch and deposit eggs below water level onto vegetation.

In the submitted image, the material emerging is not round, not whitish, not shiny. So it's frass.