In my experience, the only 2 mobile phone companies whose phones drain battery too fast are Apple and Samsung. Apple does this deliberately for older phones, whereas Samsung has this problem even for new phones.
You will not find this quick battery drain problem in Motorola, Nokia, Oppo, Sony, etc. Their phones last several years even with ageing batteries. An 10+ years old Oppo phone I have, still holds almost full charge at idle, throughout the day.
As batteries get older, their capacity to hold charge reduces, but if a phone battery is draining too fast even in idle mode, it is likely due to software, not hardware. And if it is due to software, then the manufacturer company is to blame.
I don't think you can find any evidence of a
Apple actually deliberately doing things to make batteries drain faster on older models.
That would either require hurting the battery life on all models or require distinguishable behaviours that only occur on specific models and would be relatively simple to prove through reverse engineering.
Apple has been fined for the throttling, but hasn't ever been credibly accused of actually deliberately taking steps to reduce battery life on older devices.
You will not find this quick battery drain problem in Motorola, Nokia, Oppo, Sony, etc. Their phones last several years even with ageing batteries. An 10+ years old Oppo phone I have, still holds almost full charge at idle, throughout the day.
As batteries get older, their capacity to hold charge reduces, but if a phone battery is draining too fast even in idle mode, it is likely due to software, not hardware. And if it is due to software, then the manufacturer company is to blame.