Yeah, I am careful about charging, I use a slow charger unless it is an emergency (I think I have used the box fast charger brick only twice), and I only use the cable (no wireless charging), but even when it was new I would fill it up entirely (I have a smart outlet that only lets it stay charging for ~4 hours each night), then drain it to 0% each day, so that puts a lot of stress on the battery.
I usually upgrade every 2 years now that phones have non-removable batteries. I do, however, still have working Motorola phones from the last ~6-8 years (some even with physical keyboards) that have replaceable batteries (I used to buy 2 batteries along with the phone in case they stopped making them so I could use the phone for many years), and they work and keep a charge to this day, and I will occasionally use them as a backup if I forget to plug in my current phone (although they will soon be loosing 3G support on Verizon US and are on an ancient version of android). It’s kinda ironic that the old solution is so clearly better than the new solution.
It’s really sad that companies dropped the removable batteries (not just phones, but in many laptops too). I guess they (correctly) figure that if we can’t extend the life of our phones we will just buy new phones, but it is really sad to have to stop using a device because one part failed.
One of the reasons im thinking of buying the Librem phone (along with the privacy stuff) is that it, as expensive at it is, has a removable battery so I could use it for ~5 years.