It's hard to be sure but those look like mites or something.root aphids have 2 little bits like a exhaust pipe on a car but one on each side.if u can get a couple out under natural sunlight on a piece or paper or something we can maybe get a better shot a identifying whatever it is.if it's root aphids they can be identified by the wee exhaust pipes on each side at the back of the bug.
My first instinct was it looks like a mite.if you have a lot of life in your medium there's sometimes small predator mites that feed on them but what u have looks bigger than the predator mites though.
Have you noticed any slowing of growth or lack of vigor or anything to suggest your root zones been compromised?
If you have $25/30 I suggest you buy some nematodes for fungus gnats.theyr sold as nematodes for fg but those nematodes should kill any and all insect life in your soil.it won't affect beneficial bacteria or anything.i read they should kill all insects in the soil but at the same time I,v never personally used em on root aphids.thankfully I v never had em but I,v seen people on here who did and they had to scrap they'r whole grow and dump everything but the lights and fans which they thoroughly cleaned.they even got rid of the carpets.waited a few months bought all new pots,new Mylar for the walls,new carbon filters etc etc and got a grow going.within a few weeks they were infested with root aphids again.
They'r not a pest I would like to deal with no matter what the people selling those nematodes say they can do.if I did have ra though I would give the nematodes a try.i hope that's not what u have though
