Is money sent by a brother as assistance considered a debt that must be repaid after his death, especially given the absence of proof and a dispute over the amount, and does this debt factor into the inheritance?

If the giver and receiver disagree on the nature of the money given, the statement of the giver is accepted, unless the receiver is poor and the giver claims it was a loan, in which case the statement of the poor person is accepted. As for fixed debts, they are repaid in kind, not by their value, and are not linked to price levels, inflation, or other currencies. All debts owed to the deceased are considered part of their estate and are distributed among all their legal heirs according to their prescribed shares, not restricted to some of them.