IssueTracker

Hi, please share the stacktrace as the specifics are important.

and a full repro if possible

This snippet reproduces the issue:

@OptIn(ExperimentalMaterial3Api::class)
@Preview
@Composable
fun Repro() {
    var isTwoLines by remember { mutableStateOf(false) }
    LaunchedEffect(isTwoLines) {
        delay(2000)
        isTwoLines = !isTwoLines
    }
    val scrollBehavior = TopAppBarDefaults.enterAlwaysScrollBehavior()
    Scaffold(
        modifier = Modifier.nestedScroll(scrollBehavior.nestedScrollConnection),
        topBar = {
            MediumTopAppBar(
                title = {
                    Text(
                        if (isTwoLines) "Medium\nTopAppBar" else "Medium TopAppBar",
                    )
                },
                scrollBehavior = scrollBehavior
            )
        },
    ) { innerPadding ->
        LazyColumn(
            contentPadding = innerPadding,
            verticalArrangement = Arrangement.spacedBy(8.dp)
        ) {
            val list = (0..75).map { it.toString() }
            items(count = list.size) {
                Text(
                    text = "${scrollBehavior.state.heightOffsetLimit}",
                    style = MaterialTheme.typography.bodyLarge,
                    modifier = Modifier.fillMaxWidth().padding(horizontal = 16.dp)
                )
            }
        }
    }
}

As the size of the title changes, the heightOffsetLimit changes the value.

Since TopAppBarState is @Stable, this should be guaranteed to be observable:

 * 2) When a public property of the type changes, composition will be notified.

However, when scrolling, different items can show different values for the heightOffsetLimit, which indicates that composition is not being notified when the heightOffsetLimit changes because the items reading the heightOffsetLimit are not recomposing, which breaks the @Stable contract.