This is interesting.
I have uploaded a number of screen shots above that you can view and read.
The point of what Im uploading, as far as Histogram is concerned, is that a BRIGHTNESS histogram is the wrong histogram for an experienced tog to look at to decide is a shot is overexposed; the individual R, G and B channel histograms are much better. In this case, they will show that its largely the RED channel thats pushing the histogram to the right; and the threshold view shows the shot is actually underexposed.
The series of screen shots show how it can be seen, and how using the threshold to mark brightest and darkets points, then using the Curves dropper can help; there is a down side, and that is any colour cast, as in one that should be there, is removed.
The exif shows an auto WB Tracey, though to be honest, this looks very red for auto; unless you have adjusted Auto to be warmer (which you can do).
The worrying thing is that the image has significant noise, but an odd, radial line -like noise. Is it possibel that you has been running a number of longer exposures around this time? I ask as it possible the sensor was physically hot when this was shot; and using long exposure noise reduction may have helped. This is all guesswork, as I wasnt there.
So can you shed any light on this? Have you cleaned you sensor recently? Have you checked the sensor for de-lamination, - some layers of the protective surface can flake off and older sensor thats cleaned a lot? Not trying to worry you, - its unlikely.
So let me know if this helps.
BTW, ETTR should be used only for RAW, as you can retrieve all the upper dynamic range from a RAW shot in the converter; the theory is that the right side third contains 60%+ of the digital data in the file. Not for JPEG.