How do I stop unwanted beeping sound of my AirTag?

That behavior is normal and as-designed.

It’s intended to alert anyone that they are at-risk of being tracked. (this includes thieves)

Airtags don’t know where they are but they DO contain an accelerometer so they know when they’ve been moved.

After it figures out that your phone is nearby it no longer beeps.

the way airtags works is they do not have any sort of gps or any sort of communication other than bluetooth so a so and so 30meter range

if your airtag is out of range of your iphone then it can piggybag on other iphones within range with an active internet connection and bluetooth enabled so it will trigger the iphone in range to send the iphones gps location to your apple account as being the so and so airtags pocation so you can view it in the find me app

if the airtag is outside of range of an iphone it's 100% dead in the water.

You’re most welcome. 👋