Welcome to OverGrow @Bestbudz! 99 is correct, they need food. Happy Frog's NPK ratio is 4-1-7 iirc, so your 50/50 mix of media would be like 4-.5-3.5. Not enough nutrients imho. I was feeding my WW's 8ml each Sensi Grow A+B and 1 tsp Epsom salts at day 18 (99-22-122-39-69) N-P-K-Mg-Ca.
Those spots look to be the start of a Mg deficiency ime. There's no Mg in the Sensi Grow. I'd mix 1 tsp Epsom salts in a gal H2O, add Grow A to the solution, then add Grow B. Check EC & dilute to your preferred EC (.6-.8). they should show improvement in a couple days. Hope this helps. Just my .02!