What is the ruling on someone who backbit about a person, then repented and forgot their backbiting, then remembered it?

Backbiting is forbidden and considered one of the major sins. The conditions for repentance from it include seeking forgiveness from the person you backbit if they are aware of it, or seeking general pardon without detailing the offense if they are unaware, along with supplicating for them and mentioning them positively in the gatherings where you backbit them. Forgetting the incident absolves the sin.