Why battery service?
Why battery service?
iPhone XS Max, iOS 15
Hello! Are you asking about your phone giving you the battery service message? Apple considers a battery at end-of-life when its maximum capacity goes below 80%. Batteries are considered consumables. The phone may continue to work but will get slower and may randomly shut off, etc. You can visit an Apple Store or reach out to Apple Support to arrange replacement. I hope this helps answer your question!
Battery support - iPhone Battery Replacement - Official Apple Support