On my 6 pro, I got 2x advertised battery life until I installed one copy of Google Play services. Then I got advertised battery life.
It should be easy enough to uninstall Google’s stuff for a week and measure battery drain, then put it back.
Even with it though, I wasn’t losing 30% overnight. There’s probably some other problem. Maybe wipe + reinstall, then try with and without the 24/7 surveillance daemons?