It can be very very harmful, with pretty much no benefits. The claim that it helps prevent spread of sti's is thoroughly debunked, and a person's risk of getting penile cancer is way lower than the risk of complications from circumcision. The claim that is easier as a baby is also VERY thoroughly bullshit, on account of a baby's foreskin is literally attached to their penis and has to be ripped away. All that pain and risk and long-term damage for basically nothing, it's kinda fucked up that it's still as common as it is