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kotlinlang

I’m having some very inconsistent behavior doing an alpha scroll animation with `derivedStateOf` :thread:

With the following code:
```val groupLazyListState = rememberLazyListState()

val topBarBackgroundAlpha by remember(groupLazyListState) {
    derivedStateOf {
        val layoutInfo = groupLazyListState.layoutInfo
        val itemInfo = layoutInfo.visibleItemsInfo
            .firstOrNull { it.contentType == ImmersiveCollectionUiModel::class }
            ?: return@derivedStateOf 1f

        val adjustedOffset = itemInfo.offset.absoluteValue - layoutInfo.viewportStartOffset
        adjustedOffset / itemInfo.size.toFloat()
    }
}```
I have some top menu items where I completely switch the following `Group` composable. This ends up being totally new `LazyColumns` underneath, but using the same `LazyListState`.
```Group(
    model = group,
    lazyListState = groupLazyListState,
)```
When I’m switching between these menu items, I’ll end up in a state where `derivedStateOf` stops being called and my `topBarBackgroundAlpha` no longer changes. `Group` is totally fine, scroll is working fine, its just that observing those scroll state changes will no longer work.

What am I missing here?

I guess the issue must be similar to <https://issuetracker.google.com/issues/294436482>
`rememberUpdatedState` seems to solve it, but its not very obvious right away why `derivedStateOf` doesn’t retrigger on updated `layoutInfo` .