I've probably seen it all but nothing like that. I had a bit of sun scald this year but it bleaches out a bit more
than that and burns the leaf density to a paper thin spot and falls hollow then browns quickly. Rugosa leaves
take a bit longer to crisp but they never look like that.
That looks shiny like thin oil paint. Any Canadian geese flocks flying over,
Maybe take a few picks of other leaves on the plant and is it just on outside leaves, lower leaves, or newer
growth. ?