Will the intangible and tangible grievances of people against the oppressor be dropped if the oppressed person had wronged the oppressor more than what was done to them?

Another person's disobedience to Allah regarding you does not permit you to disobey Allah regarding them. If someone wrongs you, for example, through backbiting, it is not permissible for you to backbite them. Rather, you should seek forgiveness for them, pray for them, and mention their good qualities in the gatherings where you backbit them. As for your right, Allah will secure it for you. And if you both do not repent, retribution will be exacted from both of you in the Hereafter.