Apple's iOS 14.5 beta that is currently in testing introduces a new process for recalibrating the battery health specifically on the iPhone 11, 11 Pro, and 11 Pro Max.
Apple states this update will address an inaccurate reading of the battery health reports that some users have encountered. Apple reports this update will be out some time later this spring.
Symptoms of this bug include unexpected battery drain behavior, or in some cases, reduced peak performance capability. Apple says that the inaccurate battery health reporting does not reflect an issue with the actual battery health.
More information can be found here.