I'm upgrading my motherboard. Just took off my waterblock, and this is what the mating surfaces looked like after about a year. Does it look OK? Should I have used a bit more TIM?
This looks fine to me. You probably could have used slightly less paste even, but it's not overdone so as to hinder cooling performance. I wouldn't use any more TIM than what you have in the pictures.
+1 It is a bit thick. You might want to check the flatness of the mating surfaces. the TIM looks a bit thinner in the middle which suggests a convex surface on the chip or cooler head. I would suggest a splotch of TIM about this size -> O <- in the middle of the Ryzen's heat spreader - and nowhere else. Let the cooler's pressure and chip heat spread it out evenly.