iOS 26 SwiftUI .glassEffect() renders dark/gray on physical device - TestFlight doesn't fix it .glassEffect() renders as dark/muddy gray on my physical iPhone instead of the light frosted glass like Apple Music's tab bar. What I've confirmed: Same code works perfectly on iOS Simulator Apple Music and other Apple apps show correct Liquid Glass on same device Brand new Xcode project with just .glassEffect() also renders dark TestFlight build (App Store signing) has the SAME problem - still dark/gray This rules out developer signing vs App Store signing as the cause What I've tried: Clean build, delete derived data, reinstall app Completely reinstalled Xcode All accessibility settings correct (Reduce Transparency OFF, Liquid Glass set to Clear) Disabled Metal diagnostics Debug and Release builds Added window configuration for Extended sRGB/P3 color space Added AppDelegate with configureWindowForLiquidGlass() Tried .preferredColorScheme(nil) Tried background animation to force "live" rendering Environment: iPhone 17 Pro, iOS 26.3 Xcode 26.2 macOS 26.3 The question: Why does .glassEffect() work for Apple's apps but not third party apps, even with App Store signing via TestFlight? What am I missing?