×2Had it internally pipped? Discoloration like that is usually from moisture leaking thru the membrane, either by a pip or even an attempted pip. Or could have been from the extra number of days at higher humidity.
ETA sometimes if they try to pip on the wrong end or outside of the air cell, we will see bruising like that because moisture from inside the membrane has touched the inside of the shell.
My guess is that it pipped internally and then couldn't make the external pip.

However. .
Regarding the yolk. . am I correct in saying that they don't start absorbing the yolk until they start breathing oxygen? If it didn't ever internally pip that might explain why so much yolk.
I think that is why assisting is such a slow process to allow time for the bird to breathe and absorb.