It's likely discolored from something that was resting on it, or that it was resting on. This doesn't look like an unevenness in the planchet, at least not to me.
maybe it was taped into a folder at one time. I came across a bunch of coins that were taped into a folder that left wide stripes on it.
need to know if its elevated at all, might be a strike thru error....it lookes softened in the band area.
I believe @Clawcoins has this diagnosed. That was my immediate thought when seeing this specimen. When the punchout in a folder cannot retain the coin, folks may resort to sticking tape on the back. And if that doesn't work, then a spot of tape across the front. Exposures over time are different as a result and once the liberated coin finds its way back into circulation, toning may gradually bring closer continuity, but perhaps never completely matching appearances. This looks like that to me.
Looks to me to be struck through a paper shred. Weakness at the highest points of the die. Not sure if tape that narrow would hold the coin in place.
Have you tried to run a soft point (like a wooden tooth pick, or soft plastic point) over it to determine if the area is raised or depressed? I'd go with the environmental damage, i.e. tape, as others have mentioned.
I wonder if I'm the only one on the planet that has ever used scissors to cut tape lengthwise to make the width less and mess it up. If you look closely you may be able to see non-straight "edges" .. all depending upon what you consider a surface texture deviation. Black lines are all the same length. Purple is what I think is the movement over the coin. matter of fact if you really look you can see even more deviation in the "line" the top Red you can see a slight shift up over the back of the head/neck, then a shift down going from the back of the jaw to the front of the jaw The red/yellows you can see the surface anomaly go downwards. Looks like a flat piece of something that may have been slightly ripped on one side if it was tape. Of course, unless you were that person doing this it's just speculation. but then maybe ... we're over analyzing it ? I think I'll go back to throwing coins in dry ice, then boiling water to make lamination errors then throw them back into circulation.
