Yellow-ish leaves and brown spots

Curled leaves are heat stress from the looks of it and I would guess at underwatering for your other problems. If it’s been too hot or the light too close, they are likely to be dehydrated as well. Biobizz is tough as with organic grows you often see the issue days, sometimes weeks after it occurred. This makes it very hard to troubleshoot. I had exactly the same kind of issue with my first grow ‘Wanda - week 10’.