At face value, this looks like a hot pixel? Looking around in the attached file, I can see what I think are other hot (as well as cold) pixels where the tone of the individual pixel doesn’t really match the tones that surround it?
If it is a hot pixel, it appears to be in a darker/noisier area of the attached image so it looks quite prominent.
Of course, this is pure speculation on my part based on what I have seen in my own images.
Cheers
Dennis