Maximum battery capacity of iPhone and Apple Watch. Bad?

Hello,

I bought an iPhone 13 Pro from Swappie in July. It was at 89% capacity. Now it's down to 83%. I bought my Apple Watch 4 used from a private seller around the same time (the battery, etc., has never been replaced, and the seller was also very reputable). It's now at 78%, compared to 89% before.

I've always been relatively careful with charging my devices, but of course, I use them daily. I previously owned an Apple Watch 3 and an iPhone XS for three years. Both were previously used. The iPhone started at 85%, but after three years it was down to 78%. The Apple Watch was at 80%, but after three years it was down to 76%.

I used my old devices just as much as my new ones, yet they lasted much longer. Of course, neither device is the latest model and was used, but so were my old devices. I'm a bit disappointed. I wear the watch every day, but I use it comparatively little. In the past few months, both devices have deteriorated dramatically. I find that annoying, and it sounds like planned obsolescence to me. Aren't they supposed to last long? Probably.

How is it for you? Is this normal? Is there anything you can do about it?

PS: Of course, these things are used and not new, but my old devices have already lasted longer than my "new" ones after just a few months. I simply want to get a lot of use out of them and not have to replace the battery every year. Apple is completely terrible when it comes to batteries anyway.