Strange background flicker when using .glassEffect in a horizontal ScrollView

I am trying to apply .glassEffect to some controls that are in a horizontal scroll view in a bottom .safeAreaBar.

No matter what I try, there is a persistent pesky flickering of the background that I can't get rid of. It happens when swiping left in the bottom safe area bar to access the next set of controls.

So far, I tried:

• Wrapping either controls or the stacks in GlassEffectContainer
• Removing .interactive() from glass effects
• .drawingGroup() (incompatible with glass effects)
• .compositingGroup() and .geometryGroup() change nothing
• Tuning spacing/margins (only partially helped)

Removing the .glassEffect() from all controls fixes the flicker, but I want to use it to keep it consistent with other controls present on screen.

Any suggestions?

Here's the reproducible code and a screen recording:

import SwiftUI

struct GlassEffectScrollTest: View {
    // Mock state
    @State private var selectedOption1: MockOption = .option1
    @State private var selectedOption2: MockOption = .optionA
    @State private var value1: Double = 12
    @State private var value2: Double = 20
    @State private var showHighlight: Bool = false

    var body: some View {
        NavigationStack {
            if #available(iOS 26.0, *) {
                ScrollView {
                    VStack(spacing: 0) {
                        ForEach(0..<50, id: \.self) { index in
                            VStack(alignment: .leading, spacing: 8) {
                                Text("Item \(index + 1)")
                                    .font(.headline)
                                Text("This is some sample content that will scroll beneath the toolbar. The toolbar should maintain a soft edge blur effect as this content scrolls underneath it.")
                                    .font(.subheadline)
                                    .foregroundStyle(.secondary)
                                    .fixedSize(horizontal: false, vertical: true)
                            }
                            .frame(maxWidth: .infinity, alignment: .leading)
                            .padding()
                            .background(Color(.systemBackground), in: .rect(cornerRadius: 12))
                            .padding(.horizontal)
                            .padding(.vertical, 6)
                        }
                    }
                    .padding(.top)
                }
                .background(Color(.systemGroupedBackground))
                .safeAreaBar(edge: .bottom) {
                    mockToolbar()
                }
                .navigationTitle("Glass Effect Test")
            } else {
                // Fallback on earlier versions
            }
        }
    }

    @ViewBuilder
    private func mockToolbar() -> some View {
        if #available(iOS 26.0, *) {
            ScrollView(.horizontal, showsIndicators: false) {
                HStack(spacing: 24) {
                    // Section 1: Font controls mockup
                    HStack(spacing: 16) {
                        Picker("Option 1", selection: $selectedOption1) {
                            ForEach(MockOption.allCases) { option in
                                Text(option.rawValue).tag(option)
                            }
                        }
                        .pickerStyle(.menu)
                        .labelsHidden()
                        .fixedSize()
                        .controlSize(.small)
                        .glassEffect(.clear, in: .capsule)

                        Toggle(isOn: $showHighlight) {
                            Image(systemName: "highlighter")
                                .contentTransition(.symbolEffect(.replace))
                                .font(.subheadline)
                                .foregroundStyle(.tint)
                        }
                        .toggleStyle(.button)
                        .tint(.yellow)
                        .glassEffect(.clear, in: .capsule)

                        Spacer()

                        Text("\(Int(value1))pt")
                            .foregroundStyle(.secondary)
                            .font(.subheadline)
                            .frame(minWidth: 35, alignment: .trailing)

                        Stepper("", value: $value1, in: 8...32, step: 1)
                            .labelsHidden()
                            .fixedSize()
                            .controlSize(.small)
                            .glassEffect(.clear, in: .capsule)
                    }
                    .containerRelativeFrame(.horizontal)

                    // Section 2: Spacing controls mockup
                    HStack(spacing: 16) {
                        Picker("Option 2", selection: $selectedOption2) {
                            ForEach(MockOption.allCases) { option in
                                Text(option.rawValue).tag(option)
                            }
                        }
                        .pickerStyle(.menu)
                        .fixedSize()
                        .labelsHidden()
                        .glassEffect(.clear, in: .capsule)

                        Spacer()

                        Text("\(Int(value2))pt")
                            .foregroundStyle(.secondary)
                            .font(.subheadline)
                            .frame(minWidth: 35, alignment: .trailing)

                        Stepper("", value: $value2, in: 0...50, step: 2)
                            .labelsHidden()
                            .glassEffect(.clear, in: .capsule)
                    }
                    .containerRelativeFrame(.horizontal)
                }
                .scrollTargetLayout()
            }
            .scrollTargetBehavior(.viewAligned)
            .scrollContentBackground(.hidden)
            .padding(.vertical, 20)
            .contentMargins(.horizontal, 24, for: .scrollContent)
            .containerRelativeFrame(.horizontal)
            .overlay(alignment: .bottom) {
                Text("Swipe horizontally for more tools \(Image(systemName: "hand.draw.fill"))")
                    .font(.caption2)
                    .foregroundStyle(.tertiary)
                // .padding(.bottom, 4)
                    .padding(.top, 10)
            }
        }
    }
}

// Mock data
enum MockOption: String, CaseIterable, Identifiable {
    case option1 = "Option 1"
    case option2 = "Option 2"
    case option3 = "Option 3"
    case optionA = "Option A"
    case optionB = "Option B"
    case optionC = "Option C"

    var id: String { rawValue }
}

#Preview {
    GlassEffectScrollTest()
}