Is the money paid for a spoiled food product and waiving defamation of the company permissible (halal)? If so, is it permissible to share it with whoever helped in recovering the right? If it is not permissible (halal), is it permissible to take it and spend it on charitable causes? What about the compensation for those who exerted effort in the case? And is it permissible to defame the company?

It is not permissible to take money in exchange for remaining silent about filing a lawsuit against a company and demanding compensation if there is no material harm, even if the money will be spent on charitable causes. A company's deception by manufacturing defective goods is a right of Allah that must be prevented, not a financial right that can be exchanged. If it is highly probable that the company will rectify the defect, it is better to cover for them. Furthermore, anyone who assists in obtaining this money does not deserve a fee, because it is assistance in an impermissible matter.