So, finally discovered the battery drain cause, despite the battery setting not telling me anything. I use Wallop as a live wallpaper app. Under Android 9, it was obviously optimised to work well but hasn't been optimised for Android 10 yet. As soon as I removed it, all has been well and battery life is as good, if not better, with A10. I am not looking at 9h 50m screen on time with 120Hz, no battery saving other than killing background apps that are taking the mickey. Hope this helps someone else to figure out their causes as it looks like some apps just aren't optimised yet.
