You sould use WindowInsets.displayCutout Like this

Scaffold() { innerPadding ->
            Column(
                modifier = Modifier
                      .fillMaxSize()
                      .padding(innerPadding) 
.windowInsetsPadding(your'sWindowInsets.union(WindowInsets.displayCutout))
            ) {
                Button(onClick = {
                    interstitialAd?.show(this@MainActivity)
                }) {
                    Text(
                        text = "Show fullscreen ad"
                    )
                }
            }
        }