My last one was 10 pro and battery is essentially dead after 2.5 years of usage. Can't make half of a day, literally unusable, and I'm not a big phone user. Case is made of some really good material, which feels very premium, but runs son fckn hot that you can't hold it in your hands anymore, this is especially true during hot summers, and it got only worse with the last major OS update. This is a heat dissipation issue caused by the materials used, large battery, and hi performance CPU cores so I don't think my case was any special than the others.

I see that the OnePlus 15 follows the same route, and although it has good reviews, and they claim they solved the battery heat dissipation and detoriation issues with some new kind of cells, it seems that it still runs hot according to some reviews I've seen on the yt.

Before that I had OnePlus 7 and more budget friendly Nord, and they were much better than 10 Pro, although 7 shared similar type of issues as 10 Pro. Nord is a bit different because case is not premium, and the battery is not so large, and the CPU is not premium nor the supercharging as well. However, it doesn't run hot and battery after few years of usage is still able to give you a full day without the problem.

I'm pretty convinced that all their flagships with hi performance CPUs, premium case, large battery, and fast charging suffer from the same issues.

Maybe mixed CPU core architecture is an answer to that issue, which might suggest why is so prevailing in other phone manufacturers but I have not dig that deep into the topic