bleached or powder washed is my guess.
if ya look at the borders on each side of mick's face,
looks like the heavier stains did not fully release.
that corner mighta been rebuilt as previously mentioned,
but all of the corners are the exact same color as the rest of the card
which leads me to believe it was bleached/washed as well.
it does leave a distinct smell so
wouldn't be able to tell now as it's encased.
a simple black light would be able to distinguish if it was rebuilt or not:
