They look as if they have cooked. Also the veins look rather pale as if they've been in too dark a spot. Are they in a bright but not full sun position? The bag shouldn't be touching the plant. Try blowing the bag up and putting it over the pot quickly before it has deflated. You might need a larger bag. Use a rubber band to fix it round the pot. Remove any leaves which go brown. The growing tips look ok so be patient. Don't throw them away.

If you live somewhere with a reasonably mild winter you can root Hydrangea by sticking hard wood cuttings into the ground and forgetting about them for a few months.

Does that pot have a drainage hole?

Yes it does have a drainage hole. Should I keep it under fluorescent lighting? I’ll pick up the bag a little or get a larger one. Thanks for the tips!

I stick cuttings in pots of pine bark fines mixed with potting soil. Half & half. Wet good and put them in dappled light outside. Uncovered. The do great! I do live in the lower SE so it is hot and humid. I will leave the rooted ones in the pot, over the winter, and they sprout back in the spring.

I live in Northeast United States so right now it’s hot and humid, but with fall around the corner I don’t think they’ll do well outside...