It is kinda baldspot but not swollen or no bump and also mom and dad they don't have itAssuming that is fur and not a bald sport or swollen bump nothing to worry about. What did mom and dad look like? Puppy coats and markings can change as they mature and is based on the genetics.
No it's not mange I already checked but I will double check with vet thanks*Shepherd.
If that's a bald spot then you should call a vet and make sure it's not mange or something of that sort. There is no way for us to know if it's a health issue.
If it's just the coloring of the hair - it's part of the dog's mask that will increase in the tan area as the dog matures.