Is money considered lawful if its source is investment certificates on which is written, "Interest rate is calculated at 12%" and "The maturity value of this certificate is determined according to prevailing rates until the maturity date and is paid at the end of the term"?

Investment certificates of all types are forbidden because they involve usurious interest, whether fixed or unfixed. The principal capital must be withdrawn from the usurious bank, and the usurious interest must be disposed of by spending it on charitable causes. Repentance to Allah for this forbidden transaction is also obligatory, "But if you do not, then be aware of a war from Allah and His Messenger. And if you repent, you will have your principal — you will not be wronged, nor will you wrong [others]."