Battery drains 1% every minutes

I use my phone at night, then before i sleep, i do this on my phone:

1. Locking auto-rotate
2. Turning on do not disturb
3. Brightness at 0%
4. Volume at 0%
5. Turning on low power mode

after 9 hours of sleep, when i am using my phone again, i noticed that the battery is draining like 1% every 1~2 minutes and i was disappointed when i see those. This battery was changed on about february 2019 and its still no problem today, but i wonder why it drains so fast.