Your brother tries to conceal his deeds to avoid riyaah. So try not to expose him too. Sometimes we have the tendency to post this and that good deeds done by a friend. I think we should keep this to ourselves unless it is beneficial for others. Protect your niyyah and protect your brother’s niyyah too.
This is just as Abdullah ibn Mubaarak said to the man who pulled of his mask during a battle against Roman “Abu ‘Umar, you are amongst those who exposes us?”