My OnePlus 3 goes to sleep way too fast, what's the issue?

[AC Question]

I have a OnePlus 3 running OxygenOS 3.2.6 and my phone goes to sleep way too fast (the default I have set is 15 seconds) but it goes to sleep within like 5 seconds and happens even in games if im inactive for like 5 seconds.

What seems to be the issue?

 

[belodion]

It may be worth contacting the manufacturer's customer support.

 

[B. Diddy]

Welcome to Android Central! Any 3rd party battery-saver apps installed?