Is it normal to have a bruise after 3 months of PRP in the undereye area? (Photos)

It looks like you got a bruise from the needle. Most of the red blood cells are taken out when PRP is prepared, so the dark discoloration came from bleeding in the area caused by the needle. In other words, you got a black eye, which is a risk whenever you get an injection regardless of whether it is PRP, filler or even Botox. The discoloration should go away in time, but there is a risk that some staining of the skin from the iron in the blood could persist indefinitely. If you get injected again in the future, I would suggest seeing a doctor who is skilled with cannulas. You can still bruise with a cannula, but the risk is much less.