GrapheneOS devs can't access your devices and each update is signed off by multiple parties working for GrapheneOS. They even removed all his access once they noticed his absence. If any code had been pushed by someone else in his name, they would've known already and disclosed as much. If you're having issues, check the forums or see if there's a pending update you haven't installed yet. If nothing else helps, check reset options in system settings (take a backup beforehand!) - you can just reset networking or some app preferences instead of doing a full factory reset.