Is the Zakat paid for building a mosque and sponsoring an orphan valid and acceptable, given that the payer was unaware of the impermissibility of spending Zakat on these items?

Allah Almighty clarified the categories for zakat expenditure in His saying: (Indeed, [prescribed] charitable donations are only to be given to the poor and the needy, and to those who work on [collecting] them, and to those whose hearts are to be reconciled, and to [free] captives, and to those in debt, and for the cause of Allah, and to the wayfarer) [At-Tawbah: 60]. The preponderant opinion is that "for the cause of Allah" refers to those striving in the cause of Allah. Accordingly, it is not permissible to disburse zakat to anyone other than these eight categories. Therefore, it is not permissible to spend it on mosque affairs according to the majority of scholars, and what has been given from it for building mosques is not sufficient and must be given again to its rightful recipients. It is permissible to give zakat for the sponsorship of a poor orphan. The acceptance of acts of worship is a matter of the unseen, and a Muslim must exert effort to have their acts of worship accepted through perfection and sincerity. The righteous predecessors feared the non-acceptance of their deeds.