Is it permissible to work as a data engineer for a consulting firm that provides internal data organization services to companies such as banks and insurance companies?

That which is forbidden is working in prohibited fields or for companies based on prohibited activities, such as usurious banks. As for work that is not specific to a forbidden field, the basic principle is that it is permissible. There is no harm in working for a technology consulting company that provides its services to general companies and institutions. However, if a specific task involves a forbidden company and serves its forbidden activity, then it is not permissible to participate in it. This is because whoever assists in an action and causes it to happen becomes a partner with its perpetrator in the consequences of their action, as Allah Almighty says: {And do not cooperate in sin and aggression}. The means have the rulings of their ends.