Honestly, not to sound stubborn, but when you tweak it, gcam becomes way better than the stock camera (I use the BSG port @ Version 8.1, my config is attached). Also sleep mode is better in MIUI? That's weird news for me, since my phone when I was running miui, could hardly get me through the day, thanks to the buggy gallery app... How many hours of Sot are you talking about there? And how many hours of idle time in total?
Don't worry, everyone has their own experience and we give our opinion according to what we experience, you don't sound stubborn.
In miui with each setting configured and without having a phone full of junk applications and having only telegram, twitter and discord as social networking or messaging apps, the battery drains between 1% and 5% depending on the day, but I would swear that this 5% was only the first day. (in suspension)
With LineageOS with android 12, either with nikgapps or mindthegapps, with Pixel Experience or ArrowOS with android 13, the battery drain in suspension has been very large, from 7% up, with Pixel Experience being the worst by far.
It may be that I do something wrong when installing a custom rom, but I follow everything that the pages say step by step, with the latest firmware, I have tried to install it from Windows, Fedora and Ubuntu, but all the results are the same, except that with Android 13 the phone does not heat up excessively, but when I used android 12 either with Lineage or Pixel Experience, the phone heats up which is nice and the battery vanished without realizing it.
It surprises me, because Miui is a much more loaded system, but, it is my experience, I also tell you that I am from Europe and I use the eea version of Miui that perhaps this leads to better optimization due to European regulations.
Regarding the camera, I can tell you the same thing as with your experience about the adjustments you made, surely you will have a better experience in Lineage than with Miui, I do not doubt it.
I am usually a sleep watch and I usually sleep between 6 or 8 hours, in that time leaving the phone on, these last days since I returned to Miui (less than a week ago) the phone does not drop even 3% in suspension.
The total time with the screen on varies a lot depending on the phone and the settings, but I think the most relevant thing is that I use the phone at 60hz and I think it's important to mention it, anyway, watching videos on Youtube I don't think it affects too much, generally with ambient brightness inside my room we're talking about 8 minutes or more for one percent battery at 1080p 60fps playback on Youtube, playing, depending on the game and if I'm away from home or on home wifi, it can go in the worst case to 3 minutes for one percent, up to 6 minutes for one percent.
I doubt it can compete with your data though, because good cpu settings are key.