The battery icon is ALWAYS lying. 100% full icon for 50-100% battery. 85% full icon for 10-49%, a low battery icon for <10%.
GNOME shell is not signaling the battery percentage honestly through its icons. It shouldn't show the full icon below about 85%. It should show the 85% full icon until no lower than ~65%, a half-full icon when near half-full, and a 20-35% icon in that range, and the 10% icon in the lowest range.