Please can someone please explain the attached BATTERY LEVEL Graphic - which shows my iphone 15 on charge between midnight and 7 a.m. but is only “Last Charged to 63%”. What does the light-green ‘greyed’ out area mean between the sloping downward battery level and the 100% Level. I don’t know why the Level should gradually fall over night - with no activity as shown on the ACTIVITY chart until after 6 a.m. (Though Charging Optimisation is set to Optimised (with a Maximum Capacity of 100%) I’ve not seen any “optimisation messages” reported)