What is the ruling on money earned from working in a company that fraudulently alters materials prohibited from export and sells non-conforming materials by falsifying inspection results? And how can one dispose of it and perform sincere repentance?

As long as the company's work is confined to forgery, deception, and fraud, it is not permissible for you to work there. What you have earned from this prohibited work is ill-gotten gain. If you were unaware of its prohibition, then there is no blame upon you for what has passed, for Allah Almighty says: "So whoever receives an admonition from his Lord and desists, he may have what has already passed, and his affair is entrusted to Allah." However, if you were aware of its prohibition, then you must dispose of what you have earned by spending it on the welfare of Muslims or giving it to the poor and needy. If you are poor and in need, there is no blame upon you for what you have spent on yourself from this money, and it is permissible for you to take from what remains of it according to your need.