MacBook Air M4 battery: Taskbar vs. settings charging status

What happens when you reboot the computer?

If a simple reboot of your Mac doesn’t fix things, see if the same thing happens in safe mode.  Safe mode will often correct weird software behavior by forcing the OS to clear caches, do disk repair and other self-maintenance and housekeeping and temporarily disables third-party mods.

How to use safe mode on your Mac - Apple Support 

You can exit safe mode by restarting your Mac normally, then reevaluate the problem.

I think you are seeing a "feature."

The battery icon in the menubar ("task bar" is a Windows thing) is superimposed by of a power plug symbol. My M4 Pro Macbook Pro shows the same.

Optimized Battery Charging will hold the charge at 80% if usage patterns suggest it is in desktop mode, and if the charge was already over 80% when that took affect, you get the reporting you see.

Let it sit that way a while longer and again check "Battery" in Settings. Mine is jut under 80% and shows "on hold."

To learn more about Optimized Battery Charging, please see:

If battery charging is paused or on hold on your Mac

What macOS version is running?

The current version of Tahoe is 26.3.

If there is another, lower version of Tahoe currently installed on the computer, consider applying the update. There are bug fixes and refinements being made.

Update macOS on Mac - Apple Support