There's evidence creatine may raise DHT levels, and DHT causes hair thinning: https://pubmed.ncbi.nlm.nih.gov/19741313/
But if you want to go down that road, there's also indications that the oil in pumpkin seeds reduce the enzymatic process that turns testosterone into DHT - so just eat some pumpkin seeds with your creatine and the problem goes away! It's that simple!!!