navigation destination com.example.myapplication3:i is unknown to this NavController 这bug怎么改啊！

你看的action_game1Fragment_to_game2Fragment 这个控件是不是fragment呢？
你看看
https://www.cnblogs.com/guanxinjing/p/12344572.html

看着是NavController 未找到，可以试试 val navHostFragment =
supportFragmentManager.findFragmentById(R.id.my_nav_host_fragment) as NavHostFragment 。然后 navHostFragment .navController

 val navHostFragment =
            supportFragmentManager.findFragmentById(R.id.my_nav_host_fragment) as NavHostFragment
        navHostFragment.navController.apply {
            addOnDestinationChangedListener { _, destination, _ ->
               setDefaultTitle(destination.label.toString())
            }
        }