Depends on brightness, which is one of the most important factors, and by itself, is the most important factor, but that said:
The Facebook app is awful in terms of battery drain. It has always been. 5.5 hours on 46% isn’t absolutely amazing, but it‘s decent. If brightness is remotely high, to get more you have to lower it, and Facebook would need to be curtailed. In fact, I am surprised it’s even at 5.5 hours with that app. It was used quite heavily by people back with the iPhone 6 and 6s, and those threads are full of people complaining about battery life, only for Facebook to be the sole culprit. I’ve never used it, but it was a frequent complaint. The rest of the apps are fine, Safari isn’t too heavy.
Overall, it’s not as awful as the initial post made me think. What’s the brightness set at?
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@rui no onna said, if brightness is high you need to decrease it to get more, otherwise it’s impossible.