Pages beyond the bounds of HorizontalPager never call onDispose | Jetpack Compose

Question

I've found strange behavior in HorizontalPager.

Pages beyond the bounds never call onDispose inside DisposableEffect. In other words, what kind of key DisposableEffect must consume in order to trigger onDispose once the page becomes "inactive"(stops composing)?

In my case, there are 5 pages of content for the pager. Using beyondBoundsPageCount == 1 there are always 2-3 pages composed at the time, while others aren't.

The screen with pager:

...

HorizontalPager(
  pageCount = pages.size,
  state = pagerState,
  beyondBoundsPageCount = 1
) { index ->
  val page = pages[index]
  PageScreen(page, index)
}

...

The page itself:

@Composable
fun PageScreen(
  pageData: PageData,
  index: Int
) {

  DisposableEffect(key1 = Unit) { // What kind of key there must be
    Timber.d("DisposableEffect body at $index")

    onDispose {
      // The block which is never gets called
      Timber.d("DisposableEffect onDispose at $index")
    }
  }
}

P.S.:

Compose version is stable 1.4.1

HorizontalPager is from androidx.compose.foundation.pager.HorizontalPager