Chosen Solution
I have an iPhone X with an intermittently fault. All external buttons (side, volume and mute switch) have a delayed response. The touchscreen is fully responsive, no lag or anything, but whenever I use any external buttons they take 1-2 seconds to respond. I’ve noticed that it also takes longer than normal to recognise when I disconnect the charger when this happens. I’ve tried performing a DFU but that didn’t fix it. I’m guessing there’s something wrong with the motherboard, but not sure what exactly is causing this. Any insight would be greatly appreciated.
Try resetting the phone after taking the full backup. if still problem persist, you need to check any liquid damage on the board or on the button cables.
