First time Indoor- White Strawberry Erdbeer

High humidity for long periods on root zone, causing lack of oxigen, water less in quantity or frecuency till you find the sweet spot.

light to much spectrum you have much red color no go up 25-30% power take 300ppfd

the single bladed leaves are often fugly like that, so no worries, but what's happening with new growth is alarming. says coco, perlite and some sort of vericucompost portion... which would contain unknown amoutns of nutes, i'm guessing? possibly some ph issues... lots of uncertainty. your water habits may be at fault too. if this is more like a soil substrate, water to ensure the entire things gets wet - a little runoff is fine but you don't want ot leach off what your compost is supposed to add, as that is contradicting behaviours. wait for top 1" to dry and repeat. easy-peasay, Though with your substrate, you probably need to re-irrigate when the top layer starts to change colors as the coco base won't have the same water capacity of a typical soil. How often you add fertilizer depends on concentration you prefer to feed at. This will cause a variance in water-only irrigations in between to make it all even out over time. if this is being run as soilless, then fertilize everytime with minimum 10% religous runoff, wait for top layer to try and repeat. key here for both.. no dry pockets. You don't pick the volume needed. The water capacity of your substrate and timing of your irrigation dictate how much water you need. don't say to yourself "i treated them all the same" clearly that plant, in that put doesn't give a fuck about that perception :P hope it's nute-related vs genetic, but not enough info to guess properly as to cause. i'm guessing rootzone issues from bad irrigation behaviour or something in that compost that's funky / out of proportion.

If you noticed a verry high EC this might just be the after math from it. It does look like some phosphorus issue to me based on the small leaves and how the damage progressed but normally that starts on the lower leaves first not the upper. So before trying to treat anything, Get your EC in line and PH then see if it is progressing, If it is not, problem solved no need for anything. If it is progressing still time to look into other options. This link is nice for a descent leaf chart. https://420life.com/wp-content/uploads/2021/10/Marijuana-Leaf-Deficiency-Chart-scaled.jpg Again fix EC and PH first before trying anything else. Plants are looking nice and healthy otherwise. Good Luck!

Lacking Phosphorous. The question is, why? Insufficient quantities? Excessive salts around the roots causing lock out? Out of Range pH? You might have too much phosphate in the soil. Are you growing in Coco? Is the coco drying out frequently?