I regularly shave and i noticed these today and im a little scared. I have a casual partner so this makes me more worried if she mightve given me something.
I've read dark spots can appear as you get older + my health hasnt been great due to corona and general laziness; but this i just dont know.
Best to get a professional medical opinion - contact your GP / Family doctor - you may be able to get a phone consultation and you can send the photo to them
Otherwise contact any sexual health service