Alought they are attracted to damp conditions it’s more lightly they are attracted to the rooten matter in the soil especially if your using organic food.
If you get them again try nematodes they will much them up in no time
What are Fungus Flies? The Fungus Fly, also known as the Sciarid Fly, can cause severe damage to plants. These tiny flies will lay eggs in compost or soil, from which larvae will develop. The larvae feed on young plants and seedlings at propagation. Fungus Fly are also a common pest in...
dragonfli.co.uk
I find myself disagreeing with autos being transplanted they don’t do well with down time
Also I’ve had some kick of flowering while only three weeks old catching me by surprise and you don’t want to transplant a flowering plant
Why bother stressing the plant. moving homes is one of the most stressfull things a plant will go through it normally takes 2-3 days to recover that’s two days growth you won’t get back
Photo periods it doesn’t matter if you get down time however with autos it does