The phenomenon of hair loss in that area is called facial alopecia, and it's a normal pattern of hair loss when cats age. There are also scent glands around the face area, which cats enjoy rubbing on things, which may contribute even more to the hair loss in that area.
I should note though that sometimes hair loss in that area can also be related to some medical issue. But if it's medical related, there will probably be other symptoms like lesions in that area, or the cat is scratching that area.
Facial alopecia is said to typically appear in cats 14 to 20 months old, so your cat is a bit young to be showing it, but I wouldn't be too worried unless you notice any other symptoms. It very probably is the case that like humans, some cats just lose their hair unusually young without any other negative effects.