Is it considered cheating to empty a product into a bag to conceal the well-known company's name and sell it at a higher price without disclosing the company's name, whether the customer asks or not?

The seller must be truthful in their answer if the buyer asks them a question. It is forbidden for them to lie or to practice deception. This is based on the Prophet's (peace and blessings be upon him) saying: "The two parties to a transaction have the option (to annul it) as long as they have not separated. If they are truthful and clarify, blessings will be bestowed upon their transaction. But if they lie and conceal, the blessing of their transaction will be removed." And based on his (peace and blessings be upon him) saying: "Whoever sells a defective item without disclosing its defect, will continuously be under the wrath of Allah, and the angels will continuously curse him." And based on his (peace and blessings be upon him) saying: "Whoever deceives us is not one of us."

If the buyer does not ask, but the seller conceals the company's name with the intention of deceiving the buyer and misleading him contrary to reality, this is a type of forbidden fraud and deception. Deception, in the sense of a person showing something different from what they conceal, is forbidden if it involves a breach of trust or a breaking of a covenant, as Al-San'ani stated in "Subul al-Salam": The Prophet (peace and blessings be upon him) forbade specific contracts that involve deception, and the jurists stipulated that the deceived party has the right to annul the contract.