I honestly don't know about the yellowing, but you do want to be careful with the netting on the peat pellets. I occasionally use them for space/ease (and basil does love the ph level and germs very quickly in them) but honestly peel it off when potting up. It breaks some roots, but they don't decompose here (dry alkaline soil) and I find the whole net wrapped around the base of plants.

Are you using lights? Fertilizer? Below 60 is too cold for basil babies--they'll stunt, but I doubt that's the cause of your yellowing. And it wouldn't bug the chives and oreg as much.

Oh, and you could pot the basils up--they've got true leaves and are pretty tough at this stage. I would wait longer on the oreg and chives to see how they pull thru.

Peat holds a lot of water. If you are watering weekly I would let it dry out. How is your lighting? Also reporting is what I would do but I snip the netting if the roots have grown through. Breaking the roots cause a lot of shock.

I potted them up and they're going crazy now! The basil is very happy. <3