Congratulation you are having fungus gnats
these little foggers
are to fight in every stage
yellowstickers and surface of the medium spraying with neemoilsolution
predators for the soil ( nematodes)
because they are laying eggs into the soil and the larvaes eating the roots of your girls
and you have to keep this regimen for weeks,
because on fly makes 200 new bBIES
but if you do like i wrote, you can fight them in a fe weeks t
and here some theretical background
https://www.growweedeasy.com/?s=fungus+gnat