Does my husband's deduction of the amounts that banks withdraw from usurious interest when he donates them to the poor make the deducted amount unlawful (haram)?

It is not permissible for a Muslim to deposit their money in an interest-based bank, except in cases of extreme necessity. In such a case, they should place it in a current account without interest. If compelled to place it in an interest-bearing account, they must dispose of this interest by spending it on the general welfare of Muslims or on the poor and needy, and they are not permitted to benefit from any part of it. As for the amount the bank deducts from the interest, if it is an administrative fee, it is not permissible to deduct it from the interest. However, if the bank takes the amount from the interest itself, there is no objection to deducting it from there.