Hi guys,
I wanted to post my experiences again. I use a Xperia X Compact (!) and the LOS 16 ROM for that one by chippa_a, so basically I am on another phone, but since our phones are similar and our ROM is developed by the same developer, I figured this could help all of us. Also, some guys here stated a similar problem as I have.
For me the ROM works great. After last update, the only problem remaining is a problem somewhat related to wifi and the airplane mode. I did a few more testing on that issue.
Let's say in the morning I boot my phone and activate wifi. For the whole day, there won't be any issues. No problem with wifi, no problem with heating-up, no problem with battery life.
For the night I always activate airplane mode. Also there, no problem at all. Phone enters deep sleep and uses ~3% battery per night, which is totally okay. Won't heat up also, in the morning the phone is cold.
THEN the strange part happens: In the morning I always deactivate airplane mode. Phone reconnects with network and wifi. From THAT moment on, the battery life is miserable. The phone uses WAY more battery than normal. Also, it starts getting hot during easy tasks like chatting in Whatsapp. If I connect it to the charger, it gets even hotter, and does load only very slowly, which I guess is expected. Something seems to keep the phone very busy. De- and reactivating wifi does not help much, too.
What does ALWAYS help is a restart. I restart the phone, battery life gets back to normal, phone cools down, even with connected wifi. Phone will function well throughout the day, very good battery life. And then, the next morning, after deactivating airplane mode, the same thing starts again.
Which de facto is not a GREAT problem, because you can easy add a daily reboot to your morning routine, but it's very strange. I also could not find any strange wakelocks or app behaviour that could cause such battery drain in the morning. Does anybody have similar experiences, or maybe a solution? Some guys here already stated similar problems with airplane mode OR with wifi and battery drain. Somebody suggested to underclock the CPU to solve this, but I do not understand how the CPU frequency is related to battery drain after leaving airplane mode...