Did you buy one of Apple’s Smart Battery Cases last year? Apple has announced that it is replacing some Smart Battery Cases for the iPhone XS, iPhone XS Max, and iPhone XR due to charging issues that could prevent the case itself from charging or stop the case from charging the iPhone. Apple produced the cases in question between January 2019 and October 2019. The company noted that these charging issues do not pose a safety hazard—the affected cases just won’t work correctly.
If you have a case exhibiting these problems, Apple will replace it for free at an Apple Store or through an Apple Authorized Service Provider (make an appointment first). Apple doesn’t provide serial number ranges or any other way to know if your case is affected; contact Apple Support if your case isn’t having problems now but might still be covered—the program is good for 2 years after the first retail sale of the unit.