The color is correct on the gun. You guys are not allowing for the oil/grease/grime that can obviously be seen on the gun which plays with light reflection, which messes with the perceived color. Combine that with unknown lighting type and unknown camera settings.
One just has to learn what the right color looks like when presented in differing conditions.
Sometimes, I wonder if some of the judgements are being made on a phone sized screen. I use a 24" monitor. That helps.
So-
The knob on this gun has a white bevel.
The color looks right to me.
I see NO sign of buffing.
One more thing-
Know the finishes. 1920s guns are very, very slightly less high polish than Pre WW I guns and 1930s guns. They were very high polish before WW I, but they came back after the War slightly less polished. They again became very high polish in the 30s, but probably one grit less on the polish in the 20s, or most of the 20s. I've never tried to pin down the exact year it went back to high polish, but it seems to be roughly about the time the decade changed.
Don't believe it? Lay a HIGH condition 1923 M&P beside a HIGH condition 1933 M&P. Put a 10x loupe on the two surfaces.

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Regards,
Lee Jarrett