End turning black is and spotty big leaves yellowing and some yellowing leaves near middle of plant tips of fan leaves dried and burnt off could it be aa mold?
Try feeding some calmag, looks like could be calcium deficiency and possibly phosphorous deficiency. The ends getting burnt could be nutrient burn, that isn’t too much to worry about at this stage
Looks to me like it's nutrient related. Most likely too much. What's your grow medium, how often are you feeding and how much. What pH are you adjusting your water/feed to.