Is money taken from a contractor in exchange for awarding him a bid considered unlawful (haram) or suspicious?

If the work for which you demand a commission is inherently part of your duties at the company, then this money is a forbidden bribe, and it is impermissible to request or accept it, as the Prophet, peace and blessings be upon him, said: "Gifts to workers are ghulūl (ill-gotten gains)." This is unless the company explicitly permits it, provided that the work itself is legitimate. As for tenders, they must be based on competition, expertise, quality, and suitable pricing. Any interference that contradicts these criteria or taking money because of it is considered ill-gotten and a betrayal.