@Composable
 fun Test() {
     var isShown by remember { mutableStateOf(false) }
     val opacity by animateFloatAsState(targetValue = if (isShown) 0f else 0.5f, label = "")
 
     Column(Modifier.statusBarsPadding()) {
         Button(
             onClick = { isShown = !isShown }) { Text(text = "Toggle text") }
         
         Text(text = "Hello world", modifier = Modifier.graphicsLayer { alpha = opacity })
     }
 }

graphicsLayer { alpha = opacity }

Modifier.animateAlpha { opacity }

@Stable
 fun Modifier.animateAlpha(alpha: () -> Float) = this.graphicsLayer {
     this.alpha = alpha()
 }

The above composable works fine. It doesn't recompose Hello world text every time, but only once.

targetValue

animateFloatAsState

without a recomposition, the

targetValue

of

animateFloatAsState

can't be updated.

Caveat: Inline composable functions

val lambda = { opacity }
val modifier = remember(lambda) {
    Modifier.animateAlpha(lambda)
}

Modifier.alpha

Modifier.Node

Why is there a

Modifier.alpha

extension, if it doesn't do what it's supposed to do

Modifier.alpha

graphicsLayer { alpha = x }