OMG it definitely looks like unabsorbed yolk. Your going to need to cover it because what will happen is the chicks will claw it with there little toes nail and break it open, if they do that your chick will not survive and if they don't claw at it the rest of the yolk could fall out and again, it will soon die. I have had a chick do this only my dog accidently step on him and sliced him opened and sure enough his yolk came all they way out, I put some neosprin on a bandaid to help keep it covered until it was able to go back up and close on it's own. it took days because like I said my chick had a open wound so the wound had to close up first then the vent closed up... But if it breaks opened it's going to be over for the little chick... why are you helping them on day 22 give them at least 5 days after the due date...
I'm not sure if you separate them and leave it uncovered if it will dry up and fall up. I would think perhaps adventurally it would, I have never tried it. the second picture it looks like the sac maybe opened, You can see a water of yolk coming out. YEK not good....