(side note) some on here might recommend expensive treatments or even replacing plants as a way of 'starting over.' My 2c is that I try to stay organic and you should be spraying or dipping your plants and probably grow media for mites. Since when has every single weed grow ever not had spider mites. Wish I could say I remember but I don't really. If you clean the grow room really well (soap and water works just as good as antibacterial xyz) and stay on top of the environment in veg, which you should be doing anyway, then it might not really matter if or where mites or mold spores are coming from. Try Bee Safe it smells better than neem oil IMO and together with physically cleaning the mites and damaged leaves off of the plants it works great. At some point I may have to start a bona fide quarantine area ideally a separate room, to keep new or shared clones and flowering plants.
I have not gotten clones free of bugs or PM in many years. Stick with seeds until you can find a keeper. I have a friend who constantly questions if my plants are clean. I have only gotten thrips from his cuts. He's never gotten any bugs from my clones.