Why does the "battery" icon show charging when it's unplugged?

My laptop's battery icon keeps showing that it is charging even when the power adapter is completely unplugged, which makes me wonder whether Windows is displaying incorrect information or something is wrong with the battery itself. The laptop seems to run normally most of the time, but the charging symbol sometimes stays on longer than expected, and I cannot figure out whether this is caused by a battery driver issue, a Windows glitch, or a hardware problem that needs further investigation.