Hi all, I’m running into a “double update” effect in SwiftUI when using the @Observable with @State. I’m trying to understand whether this is expected behavior, a misuse on my side, or a potential bug. Setup I have an observable store using the Observation macro: @Observable class AlbumStore { var albums: [Album] = [ Album(id: "1", title: "Album 1", author: "user1"), Album(id: "2", title: "Album 2", author: "user1"), Album(id: "3", title: "Album 3", author: "user1"), Album(id: "4", title: "Album 4", author: "user1"), Album(id: "5", title: "Album 5", author: "user1"), Album(id: "6", title: "Album 6", author: "user1") ] func addAlbum(_ album: Album) { albums.insert(album, at: 0) } func removeAlbum(_ album: Album) { albums.removeAll(where: { $0 == album }) } } In my view, I inject it via @Environment and also keep some local state: @Environment(AlbumStore.self) var albumStore @State private var albumToAdd: Album? I derive a computed array that depends on both the environment store and local state: private var filteredAlbums: [Album] { let albums = albumStore.albums.filter { album in if let albumToAdd { return album.id != albumToAdd.id } else { return true } } return albums } View usage Inside a horizontal ScrollView / LazyHStack, I observe changes to filteredAlbums: @ViewBuilder private func carousel() -> some View { GeometryReader { proxy in let itemWidth: CGFloat = proxy.size.width / 3 let sideMargin = (proxy.size.width - itemWidth) / 2 ScrollView(.horizontal, showsIndicators: false) { LazyHStack(spacing: 20) { ForEach(filteredAlbums, id: \.id) { album in albumItem(album: album) .frame(width: itemWidth) .scrollTransition(.interactive, axis: .horizontal) { content, phase in content .scaleEffect(phase.isIdentity ? 1.0 : 0.8) } } } .scrollTargetLayout() } .scrollTargetBehavior(.viewAligned(limitBehavior: .always)) .scrollPosition(id: $carouselScrollID, anchor: .center) .contentMargins(.horizontal, sideMargin, for: .scrollContent) .onChange(of: filteredAlbums) { old, new in print("filteredAlbums id: \(new.map { $0.id })") } } } Triggering the update When I add a new album, I do: albumToAdd = newAlbum albumStore.addAlbum(newAlbum) Expected behavior Since filteredAlbums explicitly filters out albumToAdd, I expect the result to remain unchanged. Actual behavior I consistently get two onChange callbacks, in this order: filteredAlbums id: ["E852E42A-AAEC-4360-A6A6-A95752805E2E", "1", "2", "3", "4", "5", "6"] filteredAlbums id: ["1", "2", "3", "4", "5", "6"] This suggests: The AlbumStore update (albums.insert) is observed first. The @State update (albumToAdd) is applied later. As a result, filteredAlbums is recomputed twice with different dependency snapshots. On a real iPad device, this also causes a visible scroll position jump. In the simulator, the jump is not visually observable; however, the onChange(of: filteredAlbums) callback still fires twice with the same sequence of values, indicating that the underlying state update behavior is identical. Strange observations This does not happen with ObservableObject If I replace @Observable with a classic ObservableObject + @Published: class OBAlbumStore: ObservableObject { @Published var albums: [Album] = [ Album(id: "1", title: "Album 1", author: "user1"), Album(id: "2", title: "Album 2", author: "user1"), Album(id: "3", title: "Album 3", author: "user1"), Album(id: "4", title: "Album 4", author: "user1"), Album(id: "5", title: "Album 5", author: "user1"), Album(id: "6", title: "Album 6", author: "user1") ] func addAlbum(_ album: Album) { albums.insert(album, at: 0) } func removeAlbum(_ album: Album) { albums.removeAll(where: { $0 == album }) } } …and inject it with @EnvironmentObject, the double update disappears. Removing GeometryReader also avoids the issue If I remove the surrounding GeometryReader and hardcode sizes: @ViewBuilder private func carousel() -> some View { // GeometryReader { proxy in let itemWidth: CGFloat = 400 let sideMargin: CGFloat = 410 ScrollView(.horizontal, showsIndicators: false) { LazyHStack(spacing: 20) { ForEach(filteredAlbums, id: \.id) { album in albumItem(album: album) .frame(width: itemWidth) .scrollTransition(.interactive, axis: .horizontal) { content, phase in content .scaleEffect(phase.isIdentity ? 1.0 : 0.8) } } } .scrollTargetLayout() } .scrollTargetBehavior(.viewAligned(limitBehavior: .always)) .scrollPosition(id: $carouselScrollID, anchor: .center) .contentMargins(.horizontal, sideMargin, for: .scrollContent) .onChange(of: filteredAlbums) { old, new in print("filteredAlbums id: \(new.map { $0.id })") } // } } …the double onChange no longer occurs. Questions Is this update ordering expected when using @Observable and @State? Does Observation intentionally propagate environment changes before local state updates? Is GeometryReader forcing an additional evaluation pass that exposes this ordering? Is this a known limitation / bug compared to ObservableObject? I want to understand why this behaves differently under Observation. Thanks in advance for any insights 🙏 Full Project Link