What is the ruling on money acquired from completing a deal for a product outside the scope of the company's work, using company resources, in exchange for a percentage of the profits, while the direct partner in the deal conceals it from the rest of the partners?

If the item is outside the scope of the company's work and you inform your partners about the details of the deal and the company's profit margin, there is no harm in that, even if you conceal your involvement in this work. The forbidden act is to work for your own account on an item that falls within the scope of your company's work, or to conduct a deal for yourself with your company without the knowledge of the partners, due to the suspicion of self-favoritism, as diligence for the company and seeking a low price for oneself cannot coexist. It is not permissible for an agent to buy from himself according to the jurists, unless the partners know and agree. Some of them permit it under two conditions: exceeding the announced price, and the bidding being conducted by someone else. Honesty, clarity, and transparency in transactions are always recommended to avoid disputes and gain blessings.