The S23 Fe has the same SoC than S22 so not an upgrade, more a rehashed version of it.

What is the reason to upgrade other than a good deal?

The bigger battery, the telescoping 10x telephoto, all that takes space and weights a lot. You will not find a lighter smartphone with a comparable camera system.

There are rumors that the S24U will only have a 5x telephoto lens instead of the 10x. Maybe it will weight less, but probably not much. Besides that, the S23 and S23+ have a good camera system and are significantly lighter, but no 10x telephoto and the main camera is 50 megapixel (which is more than enough). Low light performance has also been improved since the S21 series.

I use an iPhone for work. I waited until my company was done distributing these tiny old fashioned SE phones to ask them to change my 10 year old feature phone to a smartphone (and also, the speaker was broken). At least, the iPhone 11 has a decent sized screen.

You are receiving/sending data on much larger distances, it makes sense.

For the best energy efficiency, use Wifi when possible.