iOS 27 Beta 4: Native Liquid Glass UITabBar renders with opaque milky/frosted background while identical code renders correctly on iOS 26.5 Environment Xcode 27 Beta 4 iOS 27 Beta 4 UIKit UITabBarController Storyboard based application Native UITabBar (no custom tab bar implementation) Device: iPhone 17 Pro Simulator (also reproducible on other iPhone simulators) Problem After upgrading to iOS 27 Beta 4, the native Liquid Glass tab bar appears significantly more opaque (milky/frosted gray) than on iOS 26.5. The exact same application binary and configuration render correctly on iOS 26.5. No custom blur or visual effect is being applied. Current Configuration let appearance = UITabBarAppearance() appearance.configureWithDefaultBackground() appearance.backgroundColor = nil appearance.backgroundEffect = nil appearance.shadowColor = .clear tabBar.standardAppearance = appearance tabBar.scrollEdgeAppearance = appearance tabBar.isTranslucent = true tabBar.backgroundColor = nil tabBar.barTintColor = nil tabBar.backgroundImage = nil tabBar.shadowImage = nil Runtime Verification Verified at runtime: tabBar.backgroundColor == nil tabBar.barTintColor == nil tabBar.isTranslucent == true standardAppearance.backgroundColor == nil standardAppearance.backgroundEffect == nil scrollEdgeAppearance.backgroundColor == nil scrollEdgeAppearance.backgroundEffect == nil View Hierarchy The runtime hierarchy contains Apple's native Liquid Glass implementation: UITabBar _UIBarItemPlatterView _UILiquidLensView BackdropView ClearGlassView _UIPortalView _UITabSelectionView Therefore UIKit is using the Liquid Glass implementation rather than falling back to a legacy blur. Investigation Performed The following were tested without changing behavior: Removed all custom blur views Removed custom overlays Removed refresh/recomposition code Removed layout invalidation Removed transform hacks Removed PageMenu Replaced entire first tab with a plain UITableViewController Replaced DiscoverVC completely Replaced nested collection views Rebuilt a minimal demo project using identical UITabBarAppearance code The minimal demo renders correctly. The production application renders with a much more opaque gray background. Question Has anything changed in the Liquid Glass compositor or backdrop sampling behavior in iOS 27 Beta 4? Is there any new API or recommended configuration required to achieve the same transparency level as iOS 26.5? If this is expected behavior, is there any supported way to control the opacity of the system Liquid Glass material? Screenshots Attach: iOS 26.5 screenshot iOS 27 Beta 4 screenshot