I had no problems. Then I left a cup of milk in my room going bad.
Suddenly I had fruit flies and fungus gnats.
Just a few. I got rid of the food source and sprayed my plants soil with hydrogen peroxide.
Next day there were dozens of gnats flying around my plant and the lights.
So I hung a fly tape strip in the grow box and next day it was covered in a few dozen gnats.
Have only seen one or two occasional ones since.