I have had the item "System (Wakelock)" under "Battery Usage" for quite some time with a total of 1% and a current usage of 2 hrs 41 min.
I find this very strange, because in stock I never had this item.
In general, I use the device very little, the last full charge was 2 days ago and it is mostly lying around in standby.
I also only use two apps in everyday use, such as Spotify and WhatsApp.
Both are set to "Optimized" under Battery Usage.
I have a habit of exiting apps completely after each use, could this be contributing to the "wakelock" popping up?