What is the reason for a dog’s spotted nose

Poodle (detailed introduction)
A dog’s nose reflects its health and has been widely recognized by many pet owners. Those who have raised dogs know that a healthy dog's nose is cool and moist, usually black in color, but there are uncommon variations such as spotted noses or brown noses. So what causes these uncommon nose colors?
First, it should be noted that a Teddy’s nose is originally black but gradually becomes lighter, turning brown and eventually not black anymore. One type is the snow nose: during summer the Teddy’s nose is very black, but in winter, the color naturally changes to brown and lighter. Hence the name “snow nose.” This condition may be caused by a vitamin E deficiency.
Another situation that can occur in all black-nosed Teddies is disease-induced nose discoloration: conditions like vitiligo, hypothyroidism, and contact allergies can cause the nose to lose its color. These are pathological and require a veterinary check-up.
There is also a rather frustrating condition where the nose is spotted from a young age and does not change as the dog grows. This is a congenital issue caused by genetics and has no known cure. Therefore, many noses may remain discolored permanently.
In fact, as long as you love your dog no matter how it looks, and if it does not threaten health, it is acceptable. But if it is an acquired condition, you should take your dog for a check-up and supplement whatever it lacks in the body.