Apple will try to fix battery drain and reduced performance issues that have affected some iPhone 11 devices by recalibrating their batteries in an upcoming update.

According to an Apple support document, the process will happen when you update an iPhone 11, 11 Pro, or 11 Pro Max to the upcoming iOS 14.5.

Such things never happen accidentally and always happen with old iPhone models.

It might take a few weeks for the battery health system to figure out how much capacity your battery has left, and how much performance it can provide, according to the document.

And this is total bullshit, as to figure out capacity you need 2 days tops. With modern controller usually you need 2 minutes as controller store real remaining capacity in its own memory (at least it is case for almost all smartphone and notebook batteries).