Are funds taken from a buyer without his knowledge, as a result of an increase in the agreed-upon price of land between the seller and the buyer, permissible or impermissible? And what must the perpetrator do if they are impermissible?

You must return the eight million to your client, because taking a commission without his permission is considered deception and lying. You are not required to inform him of the reason; rather, it is obligatory to deliver the right to him by any possible means.