HELP! Please, I don’t know what going on

I don’t understand what’s going on to me. It looks like the yellow one from the bottom leaves in the initial leaves that give them the nutrients dying off also that they’re not getting the nutrients, but I got pro mix organic I’ve never grown in anything but cocoa and synthetics and it’s supposed to have food for three months but they’re in the little cops. They’re only a few weeks old. I had to re-up a few of them so a few of them older, one of the ones I just popped seedlings just died and dying for no reason and then one of my best and oldest ones is dying. It’s been cold at night time so I’ve had the seed mat on and I think this happened before and I was thinking it might’ve been the seed mat cause it’s hitting the roots up too much as they get older and maybe caused some sort of issue I don’t know what’s going on any advice please prepping these for outdoor never grown in their organic super soil nothing so I don’t know what’s going on, and also got cold a few nights, but that’s why I had to see Matt and the dome on still but open and then crack in it. It’s weird. I don’t know what to do. I’m already behind schedule…





I only grew in coco and organize one other time so when I googled this pro mix it said enough food for 3 month, I knew regular is like coco and you need to feed, I don’t know why when I was buying this that’s what google said but then I just google it again and it only has enough for 7-10 days , but that still don’t explain why the new seedling died, Now I know what I was thinking with the yellow is they needed food, but dying has to be light, humidity and environmental stress mixed with the root zone being to warm, I even put something in between after a few weeks because I was thinking that was the reason of seedlings dying in the past.