Is it permissible to work with skills acquired through usurious funds, and would the profits resulting from such work be lawful?

One who possesses haram (definition) (unlawful) money, such as from usury (riba) or similar sources, is not permitted to benefit from it. Rather, he must dispose of it by giving it to the poor and needy, or for the general welfare of Muslims. If he has already benefited from it, he is obliged to return its equivalent, unless he was poor and in need when he spent it. As for benefiting from skills and knowledge acquired through courses paid for with this money, there is no harm in that, because the unlawfulness is not attached to the essence of what the haram money was spent on. The rule "what is built upon falsehood is false" does not apply to this case. Rather, it means the invalidity of the subsidiary due to the invalidity of the principal, such as a reconciliation agreement based on something unlawful.