I would like to say that i hope to make this thread a sticky, and that we as community, can help each other to eliminate the problem with standby drain or any battery related issue.
I would like to open with a recent issue related to Pie, rouge apps, which results in too much battery drain on idle and overnight.
I recently disabled powergenie to maximize performance of device and make sure that my apps won't auto dim(i'll post the commands here, so you won't have to search it):
pm disable-user --user 0 com.huawei.powergenie
pm uninstall --user 0 com.huawei.powergenie
I've been monitoring the battery life ever since, and noticed at first a faster drain on idle, that's because i had some rogue dating apps that i didn't think drain too much(PowerGenie might have prevented them from over draining, even though they ran in the background).
Which brings me to the next conclusion- On android PIE, media apps might drain more power than usual, as it wasn't the case with Oreo.
Since i use various dating apps like Tinder,Grindr,OkCupid, it all might contributed to that fact, mainly tinder which was draining battery even in silent operation.
Some here are some advices: If u use dating apps, at least tinder, make sure it's not running in the background.
Instagram is also a battery sucker, facebook app is the biggest sucker, u might use facebook and messenger light.
When you go to sleep, make sure that u have no active media apps in the background, as they'll try to connect to the net even if you have turned it off(Using Airplane mode kinda defeats the purpose of low idle drain), make sure to turn off all unneeded services such as Bluetooth, Wifi, Mobile Data, Location.
I'll update it, the more i'll find, i'll post some of my recent battery life(was using phone whole night, so it didn't overdrain in the night or idle time).