Apple has released macOS Big Sur 11.2.1. The update addresses battery charging issues suffered by users with an older MacBook Pro.
macOS Big Sur 11.2.1 Fixes 2016 and 2017 MacBook Pro Charging Issue
The note accompanying the update said:
macOS Big Sur 11.2.1 addresses an issue that may prevent the battery from charging in some 2016 and 2017 MacBook Pro models.
To get the update either click on the pop-up that appears or go to Settings > Software Update and click Install Now when given the option.