I believe some phones have quality control issue. My phone is less than a month old. Barely installed any apps. I don’t game. But the phone is always hot, even on standby. Battery drains from 80 to 20 in one hour.
And since the phone is getting hot on the top portion where the motherboard lies, I don’t think it’s an issue with the battery. A faulty component in the motherboard might be drawing too much power.
Nothing needs to acknowledge this issue.