Why was the social security deduction less in September?

Hello, dear: Why did the social security deduction decrease in September? The analysis is as follows: the social security payment base is usually determined according to the average monthly salary level of employees in the previous year. The higher the payment base, the higher the monthly social security fees that employees need to pay, and vice versa. If the employee social security base is reduced, the monthly medical insurance payment will also be reduced, and finally the amount of personal medical insurance account will also be reduced. Thank you for your new trust. The above is my reply. I hope I can help you and wish you a happy life ~