I have had a few similar looking spots on the tops of my hands before after tanning that later turn darker
brown, than lighter
brown, then the disappear. This is also happening with the spots on my forearms. They went from red/purplish, to dark purple, to dark brown, and now they look like they are fading (currently light brown). I am assuming they will disappear as the ones on the tops of my hands have in the past.