If so, what was it? Any explaining the big hole in the top?
No, it is just a way of restoring Powergirls old look with a kryptonian suit. At least I suspect because of the origin that the costume has similar abilities to Supermans and Supergirls armor and won't get destroyed like the other costumes.
But the hole in the top.... no idea whatsoever. The befuddled A.I. should have given it the same S sigil-like Supergirls.
Not sure if writer and/or artists were really thinking it through beyond Editor Fiat(She must have her old look again).