Is it permissible to work for a start-up company that produces a halal product, if its capital is mixed between halal industrial companies (82.5%) and usurious banks (17.5%), taking into account that it borrowed relatively small amounts from banks to finance construction costs?

Working for someone who possesses ill-gotten wealth, in a field that is not illicit, is permissible according to the majority of scholars. This view was also favored by Shaykh al-Islam Ibn Taymiyyah, provided that the lawful wealth constitutes the majority. However, working in an illicit field is not permissible, due to the Almighty's saying: "And do not cooperate in sin and aggression." So, if the company operates in a permissible field and the proportion of ill-gotten wealth in its capital is small, then there is no objection to working for it.