This is a very interesting coin. I'm on board with a solid AU details grade and I don't see any problems as such. Maybe there is a slight granularity to the surfaces? That could easily be a photographic artifact, as could be the lack of visible luster.
This date in problem-free AU is worth close to $2000 according to the PCGS price guide. If it were mine I'd send it off for
TPG grading to get that professional grade opinion, verify authenticity, and to protect and preserve the coin. If it were offered for sale I'd wonder why it wasn't already slabbed.