My two D700s when I bought them (one new in 2012, the other used in 2017, gave me the best JPEGs out of the camera that I've had in 12 years of digi-shooting. That is until I bought my D800 last year. I've never looked back. (The D700s are nowadays still used, but mostly by my partner.)
About 18 months ago the older of the pair, with 130,000 actuations, began overexposing by up to a full stop. Maddeningly, this wasn't constant or even consistent, so I had no way of knowing if the results of any given shoot would be normally exposed or a full stop over the top. I dislike chimping on-site, so I diddled and fiddled and tested just about every variation I could think of, also several suggested by other posters on this site. At first I kept notes, but after a while I got bored with this and just scribbled words on bits of paper. I look at the latter now and find very little of what I recorded makes any sense to me. Ah, memory.
Then the second D700 with less than 20,000 actuations on the speedometer, began doing the same. Annoyed, exasperated, frustrated, maddened, I went out and bought a used D800 with 1,800 actuations, which gives me spot-on exact exposures just to my liking.
Eventually the two D700s which by then were becoming shelf queens, saw the light (a bad pun, I know) and somehow reset themselves to exposing normally. Problem resolved, in one way or another.
To this day I've no idea what if anything I did in my many tests, worked or not. I do most of my shooting on the road in Southeast Asia, with harsh light and high temperatures to contend with, much the same as living out here in rural Australia where the midday sun is enough to burn the fur off a 'roo. The three most consistent fixes I came up with, using a polarizer, adjusting the exposure compensation by one-third or two-third stops but no more (I've noted the advice from #2 in this regard and I agree with it), and setting the D-Lighting, appear to have been the closest contributors to my success in rejigging my D700s to expose correctly. Or did they fix themselves? I'll really never know.