I looked closely at your earlier pics and saw no signs of mites anywhere. They leave webs behind wherever they go and the leaves get white spots that look like salt granules which I see none of those either. Mites don't just go walking around looking for a home...they are hitch hikers and need to be brought in by either bringing them in on a new houseplant or on your clothes after being in an infested area but they can't fly and don't travel very far on their own. And young plants like those will only suffer when given pesticides so early.