The more interesting fact might be that the base xiaomi 17 with 7000 mah might have the same battery life as an 17 pro max or close to it. That means that the xiaomi 17 as a compact phone has absolutely insane battery life
The iPhone was not run at 120Hz, as can be seen from the ghosting. We will see in your own tests if the gap widens.
Also let us not forget battery size is about how often you have to recharge your phone. And indeed a big element missing from the battery testing that GSM Arena also encompasses is idle time! We can expect much smaller discharge overnight on the Xiaomi because most people's scenarios don't push the processing power, so overall the Xiaomi will require much less frequent charging, which is what battery is about.