You can replace the battery in your AirTag. Here's how.
AirTag - Wikipedia
How to replace your AirTag battery
How to Check Your iPhone's Battery Health
What to do if you find an AirTag
Apple Support App: How to Download the App & Get Help from Apple
Add an AirTag to Find My to keep track of personal items - Apple Support
This battery safety feature can break your Apple AirTags. Here's how to fix it
Apple Support sent me this message. Whats this mean？My phone was stolen one month ago, but I have locked my phone and turned on the Find My immediately. : r/iphone
eufy Security by Anker SmartTrack Card (Black, 1-Pack), Works with Apple Find My (iOS Only), Wallet Tracker, Phone Finder, Water Resistant, Up to 3-Year Battery Life(Android Not Supported) : Electronics