These images are all I can find on the metal panels. The first is from the Design and Access Statement from the original planning submission, and the second image is from the addendum. No mention of anything behind but does mention ventilation.
I've heard and read comments from people about what has been installed so far and speculation that it's windows/glazing or insulation. I'm not aware of any change to the intention for the metal panels and in my understanding a change to the facade design/appearance of this nature (eg swapping the metal panels for windows) would require a Non Material Amendment planning submission. I've had a quick look and can't find any such planning submission, but I guess it's possible.
For now I will assume that the metal panels are still the intention and whatever is currently installed/being installed will be covered by them.
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