Is it illegal for users to know that suppliers are counterfeit products?

Not illegal. It is not illegal for users to know that suppliers are counterfeit products, and the crime of producing and selling fake and inferior products is a deliberate crime. It will not constitute this crime for a general operator to sell without knowing that it is a fake and shoddy product. Article 140 of the Criminal Law of People's Republic of China (PRC): For the crime of producing and selling fake and inferior products, producers and sellers who adulterate or adulterate products, pass fake products off as genuine products, and pass unqualified products off as qualified products, and the sales amount is more than 50,000 yuan but less than 200,000 yuan, shall be sentenced to fixed-term imprisonment of not more than two years or criminal detention, and shall also be fined at least 50% but not more than two times the sales amount; If the sales amount is more than 200,000 yuan but less than 500,000 yuan, he shall be sentenced to fixed-term imprisonment of not less than two years but not more than seven years, and shall also be fined not less than 50% but not more than two times the sales amount; If the sales amount is more than 500,000 yuan but less than 2 million yuan, he shall be sentenced to fixed-term imprisonment of more than seven years, and shall also be fined more than 50% but less than two times the sales amount; If the sales amount is more than 2 million yuan, he shall be sentenced to fixed-term imprisonment of 15 years or life imprisonment, and shall also be fined more than 50% but less than 2 times the sales amount or his property shall be confiscated.