Is a son’s concealment of his bank account details from his father considered an act of disobedience (ʿuqūq), especially since the father is unforgiving and discloses minor matters, and revealing the truth might embarrass him in front of his wife and harm their relationship?

What you did is not an act of disobedience (ʿuqūq), and you are not obliged to inform your father about your wealth or show him your account if you fear that doing so would lead to negative consequences. We advise you to be kind and good to your father, to endure his harshness and ill-treatment, while gently and kindly advising him. We also warn against opening an account in an usurious bank, because the interest on it is considered consumption of usury (ribā).