Will a person be sinful if he isolates himself from people to avoid backbiting and lying, and disobeys his father's command who rejects this isolation?

If sitting with family leads to hearing or seeing something objectionable, then advice must be given first. If they respond, then mixing with them is better. But if they persist in the objectionable act and do not respond, and mixing with them corrupts one's religion, then it is obligatory to abandon it, for the Prophet, peace and blessings be upon him, said: "There is no obedience to a creature in disobedience to Allah, the Almighty, the Majestic." As for obeying parents, it is obligatory in matters that benefit them and do not harm the child, such as sleeping in a separate room. If it does not harm you, then obeying them is necessary, because a father often fears loneliness and isolation for you.