45% battery on iOS 18
25% battery on iOS 26 (which corresponds to iOS 19)
...
This is 2026
https://www.ladbible.com/technology/iphone-ios-update-26-del...
(sadly got stuck with that degraded phone because the Apple Watch that refuses to pair if you run iOS 18)
Only the iPhone XR in that test is on iOS 18. It scored behind all of the models on iOS 26.3 except for the iPhone SE. But that's not a useful comparison because who knows what condition the XR's battery is in at this point, and nothing else ran on a comparable iOS version.
Not sure what point you were trying to make with that video, but it doesn't really demonstrate cross-version battery performance.