There are multiple causes.
If you are a young or middle-aged person and the blocked pores appear around the nose, it is possible that the sebum overflow is physiological due to high androgen levels in the body and the production of sebaceous glands.
If it appears during menstruation or puberty, it may be due to endocrine disorders during that period, which stimulate the sebaceous glands to secrete too much oil and block the pores.
If you are chronically stressed, overtired, sleep deprived, or like to eat greasy food, sweets and dairy products, you may also aggravate the endocrine disorder, causing excessive sebum secretion and blocking pores.