To my eyes, this doesn't have the look of a modern counterfeit. I'm leaning toward either a contemporary counterfeit or a roughly cleaned genuine coin.
I don't have my numismatic library available right now (I'm on month 14 of a promised "3-month home remodeling"). Going from memory, the 1882 had one production coin die pair and one proof coin die pair. My records indicate that I handled two 1882 quarters over the years, but I don't have photos of those coins. It's been a while since I have seen an 1882.
My notes say the 1882 production coins have a date that slopes downward from the first "8" through the "2." I think I can see that on your coin. They also have a couple die chips or die gouges that can be used to authenticate it. One of the die chips is somewhere on Liberty's thigh SE of the bottom of the pole. The second is on or near the eagle's right leg (our visual left) somewhere in the triangle next to that leg and the feathers on the arrows and the SW corner of the shield. I can't see those areas well on your photos.
The second die pair was used only for proofs, and I think it had an obverse with a more level date or higher date. I recall that it used a reverse that had been used for earlier year proofs. That reverse has E-W die scratches at the top of the lower shield, in the background behind the vertical stripes of the lower shield. This doesn't look at all like an impaired proof, but it should be ruled in or out anyway.
Here are your whole coin photos, with the rough areas of the die chips marked with red arrows and the rough area of the proof die polishing marks circled in blue. Would it be possible to see closeups of those areas?
A final thought would be for you to contact the
Liberty Seated Collectors Club to see if anyone there could compare your coin to any of their photos of the known contemporary counterfeits.
Just some thoughts. Thanks!

