Is the money earned from working in a company that sells medical devices with specifications that violate contracts, knowing that my job is to operate the devices and follow up administratively to sign papers, considered entirely or partially unlawful gain? And is the sin removed if I explain the deficiency to the client and ask the official to compensate for it, then the official finds a devious way with the client? And is it advisable to look for another job in this case?

It is not permissible to approve the company's deception regarding devices by signing documents attesting to their conformity with specifications while you know they do not conform. This is participation in deception and a forbidden act, and the earnings derived from it are forbidden. However, earnings from work free of deception are permissible. If you can remain in the job without participating in deception, then do so; otherwise, you must leave it and seek permissible work.