Xiaomi Redmi 5 Whyred turns itself off

My Xiaomi Redmi 5 Whyred started shutting down randomly – rarely enough to make is hard to reproduce. So far happened once during a day and every 2nd night.

• I am using a Havoc-OS 2.9 (Based on Android 9) and had no problems with the system until last week, made no major changes to the system, dont even think I installed anything new.
• So far I have tried freeing up some space, because I was tight on that, made sure phone is charged and no night-only-features are on.
• Shaking phone to see if battery is not connecting somewhere gave no results – also phone turns off when on a flat surface and not moved, so I do not think that is the issue.
• Installed accubattery to see battery health but it did not provide estimate yet.
• Below I have attached a screenshot of battery usage, as you can see it is not a case of sudden battery drain.

If someone provide me with some clues about what to look for I would be greatful.