Is it permissible to anonymously report someone who sells used goods as new, knowing that this report might lead to them being deprived of their rights for a long time?

Selling a used item while deceiving the buyer into believing it is new is a forbidden deception (ghish). Enjoining what is right and forbidding what is wrong is a collective obligation (fard kifayah) and should be done by hand; if one is unable, then by tongue; and if one is unable, then by heart. It is obligatory to advise the deceiver, admonish him, remind him of Allah, and warn him by informing the company. If he does not heed the advice and persists, and informing the company would prevent him, then it is obligatory to inform them, even if the desired outcome is not expected to be achieved, according to one of the two sayings of Imam Ahmad. If the company is informed, it is not obligatory to notify the person. If financial disciplinary action (ta'zir) against the deceiver is warranted, then reporting him to the company is a permissible form of forbidding wrong (inkar al-munkar) and not a forbidden tale-bearing (wishayah).