https://wccftech.com/apples-recalibration-process-in-ios-14-5-has-increased-battery-health-percentage-for-iphone-11-users/

Apple has seen fit to seed beta 6 of its upcoming iOS 14.5 update to developers for testing purposes. While the update is just around the corner for a global rollout, the build is jam-packed with a boatload of features. One of the major and most important features to come with iOS 14.5 is oriented towards iPhone 11 owners. iOS 14.5 will include a Recalibration Process for a better health reporting system. The feature currently rests in the beta phase and users are reporting that their iPhone 11 models are seeing increased Battery Health Percentage after the Recalibration Process.

Previously, users have reported that their iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max are showing inaccurate battery health estimates. According to Apple. the recalibration process might take a few weeks once you enable it. Now that some time has passed, users are reporting that their Battery Health Percentage increased following iOS 14.5's recalibration process.