The tests conducted are being portrayed as typical use and linear when that isn't the case. There are too many variables involved that the YouTuber conveniently leaves out. The YouTuber also touts himself as a pro user, whatever that is supposed to mean. lol The video, in my opinion, is being shown through a cloudy lens.
One person may get excellent battery life with the 15 pro while another may get an hour or two less. That happens with every model. That doesn't necessarily mean that the phone that gets less with some users is "bad", as is being portrayed in the video.
With the ability for a lot of the population to charge at least once during the day, I really don't understand the obsession with so many people of not charging when they can, just because they are trying to hold Apple to some definitely battery life when Apple has never guaranteed set battery hours every time for every user under every condition.