Rw cubes in soil are not a good idea as they hold water like forever buried under the dirt. Dope plants like soil to dry and they will yellow and die if the medium is water logged 24/7. Let the medium and cube dry a lot more and scrape some soil away from the sides of the cube to allow some air...
This cheap rubbish medium is not suitable for sensitive young seedlings.Looks like an ash tray. Next time use a high quality reliable mix , peat or seed raising mix. You cant use inferior products and expect top results.
The pheno will go off. Eventually the new batch of clones will have issues and lost potency. You need to do thousands before this occurs. If you only took cuttings from the original mother it should stay the same, clone from a clone and so on is different.
What do mean you popped your head in saw a spidermite??? wtf
Put some more pics up of the underleaf before you go squirting oils and soaps all over a young seedling.
Start again this mongrel thing is fucked. It looks like everything went wrong.
Do some more research ,dust yourself off try again and pathogen control of some sort.