Give this a try: with the battery reporting low boot into Safe Mode according to How to use safe mode on your Mac and check it to see if it's the same or not. Reboot normally and check again.
NOTE: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following;
• Verifies your startup disk and attempts to repair directory issues, if needed
• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)
• Prevents Startup Items and Login Items from opening automatically
• Disables user-installed fonts
• Deletes font caches, kernel cache, and other system cache files
Have you installed and run any "cleaning", "optimizing", "speed-up", anti-virus or VPN apps on your Mac?