hi dude....
it s a case really interesting.....! if i follow well
@Spinnnn it could depend on the pot weight if it s an under or over watering... ok....but in my opinion in these 2 cases the all plant should be affected by under or over watering....😩
i mean when we see the pic....why only two leaves and not the others ?? they are nice, new and fresh...seems healthy👌 the main stem is straight....hummm
may be atmospheric explaination.....even if i think again why the all plant is not affected by the same symptoms 😕
in other hand it reminds me last year a capricious seedling of kush wich was acting like that with no reasons.....at each watering even light.....then after a moment she stops and grows like a beast....
hope this can be the same for you.....anyway if keep a good cycle wet/dry soil she will recover easily - in my opinion she's not seem to in danger for now ...for sure u have to watch her all day if any bad evolution...
but if in case
@Cat_Pied_Piper was right...u can always innoculate yourself beneficials fungi/bacterias to fight against other fungus/pest
hope this help