So I found this half roll of 1962 Franklin proofs, sealed for at least 30 years. Since the tube was only half full, they filled it up with newspaper. After 30 years like this the reverse of the coin touching the paper developed an insane toning. Would this extreme toning decrease the value, especially since its a proof?
If ya gotta use some kinda spacer in the tube, used wadded up aluminum foil! I don't know, but I would think that it would have a negative impact on the value. I wouldn't want it, but who knows.... there are a lot of folks, and some of 'em (not many) don't think like I do!
Some toning hugely brings up value, some does the opposite. It all has to do with if the toning is attractive or just distracting and blotchy. Unfortunately your coin looks to have more distracting/chaotic, blotchy toning so I think that it would negatively impact the value. Still, That coin is not very rare to begin with so the value is not hurt too bad.
There maybe one person on the entire earth who truly believes the world is flat. He may also want your coin. Find him. (eBay)