same for me.

Are you doing anything out of the ordinary in your rendering pipeline like post-processing or have texture use? Unless this is a trivial setup, I'd need to see an example. Note that camera-access currently corrupts three.js' texture state (mrdoob/three.js#26452), but AR shouldn't normally depend on that.

Okey, after some tests with android chrome, I have found out there are some warnings in debugger console.
One of the warning messages -
XR.js:200 Unrecognized feature requested: dom-overlay-for-handheld-ar

So I decided to append ARButton optionalFeatures with dom-overlay and this solution fix camera issue.

Following code fix issue for me:

<ARButton
     className="ar_button"
     sessionInit={{ optionalFeatures: [
          'local-floor', 
          'bounded-floor', 
          'hand-tracking', 
          'layers', 
          'dom-overlay'
     ] }}
/>

Fixed how? Optional features shouldn't change behavior unless they're supported. Only required features will block a request.

Well, without 'dom-overlay' feature pressing AR button leads to just fullscreen page, no AR camera, nothing just a fullscreen page. Adding 'dom-overlay' feature normalise AR button functional

@CodyJasonBennett Need to mention, despite the fact my solution fix camera issue it's also generates new warnings...))

Same here from my side as well.
Without the dom-overlay clicking on the AR Button just leads to the Full page and not opens up Camera. And by adding dom-overlay clicking on the AR Button is working fine.