diff --git a/src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs b/src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs
index ce42227292..e58abcadf0 100644
--- a/src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs
+++ b/src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs
@@ -1827,9 +1827,6 @@ namespace Avalonia.Win32.Interop
             return result;
         }
 
-        [DllImport("user32.dll")]
-        internal static extern int SetWindowCompositionAttribute(IntPtr hwnd, ref WindowCompositionAttributeData data);
-
         [Flags]
         public enum GCS : uint
         {
diff --git a/src/Windows/Avalonia.Win32/WindowImpl.cs b/src/Windows/Avalonia.Win32/WindowImpl.cs
index 057cdb2db0..3fc2751e43 100644
--- a/src/Windows/Avalonia.Win32/WindowImpl.cs
+++ b/src/Windows/Avalonia.Win32/WindowImpl.cs
@@ -371,7 +371,7 @@ namespace Avalonia.Win32
                 if (level == WindowTransparencyLevel.Transparent)
                     SetTransparencyTransparent(windowsVersion);
                 else if (level == WindowTransparencyLevel.Blur)
-                    SetTransparencyBlur(windowsVersion);
+                    continue; // Unsupported on all versions (unreachable)
                 else if (level == WindowTransparencyLevel.AcrylicBlur)
                     SetTransparencyAcrylicBlur(windowsVersion);
                 else if (level == WindowTransparencyLevel.Mica)
@@ -409,9 +409,9 @@ namespace Avalonia.Win32
             if (level == WindowTransparencyLevel.Transparent)
                 return windowsVersion >= PlatformConstants.Windows8;
 
-            // Blur only supported on Windows 8 and lower.
+            // Support for legacy, undocumented DWM blur has been removed.
             if (level == WindowTransparencyLevel.Blur)
-                return windowsVersion < PlatformConstants.Windows10;
+                return false;
 
             // Acrylic is supported on Windows >= 10.0.15063.
             if (level == WindowTransparencyLevel.AcrylicBlur)
@@ -426,37 +426,14 @@ namespace Avalonia.Win32
 
         private void SetTransparencyTransparent(Version windowsVersion)
         {
-            // Transparent only supported with composition on Windows 8+.
-            if (!_isUsingComposition || windowsVersion < PlatformConstants.Windows8)
+            // Transparent only supported with composition on Windows 10+.
+            if (!_isUsingComposition || windowsVersion < PlatformConstants.Windows10)
                 return;
 
-            if (windowsVersion < PlatformConstants.Windows10)
-            {
-                // Some of the AccentState Enum's values have different meanings on Windows 8.x than on
-                // Windows 10, hence using ACCENT_ENABLE_BLURBEHIND to disable blurbehind  ¯\_(ツ)_/¯.
-                // Hey, I'm just porting what was here before.
-                SetAccentState(AccentState.ACCENT_ENABLE_BLURBEHIND);
-                var blurInfo = new DWM_BLURBEHIND(false);
-                DwmEnableBlurBehindWindow(_hwnd, ref blurInfo);
-            }
-
             SetUseHostBackdropBrush(false);
             _blurHost?.SetBlur(BlurEffect.None);
         }
 
-        private void SetTransparencyBlur(Version windowsVersion)
-        {
-            // Blur only supported with composition on Windows 8 and lower.
-            if (!_isUsingComposition || windowsVersion >= PlatformConstants.Windows10)
-                return;
-
-            // Some of the AccentState Enum's values have different meanings on Windows 8.x than on
-            // Windows 10.
-            SetAccentState(AccentState.ACCENT_DISABLED);
-            var blurInfo = new DWM_BLURBEHIND(true);
-            DwmEnableBlurBehindWindow(_hwnd, ref blurInfo);
-        }
-
         private void SetTransparencyAcrylicBlur(Version windowsVersion)
         {
             // Acrylic blur only supported with composition on Windows >= 10.0.15063.
@@ -477,26 +454,6 @@ namespace Avalonia.Win32
             _blurHost?.SetBlur(BlurEffect.Mica);
         }
 
-        private void SetAccentState(AccentState state)
-        {
-            var accent = new AccentPolicy();
-            var accentStructSize = Marshal.SizeOf(accent);
-
-            //Some of the AccentState Enum's values have different meanings on Windows 8.x than on Windows 10
-            accent.AccentState = state;
-
-            var accentPtr = Marshal.AllocHGlobal(accentStructSize);
-            Marshal.StructureToPtr(accent, accentPtr, false);
-
-            var data = new WindowCompositionAttributeData();
-            data.Attribute = WindowCompositionAttribute.WCA_ACCENT_POLICY;
-            data.SizeOfData = accentStructSize;
-            data.Data = accentPtr;
-
-            SetWindowCompositionAttribute(_hwnd, ref data);
-            Marshal.FreeHGlobal(accentPtr);
-        }
-
         private void SetUseHostBackdropBrush(bool useHostBackdropBrush)
         {
             if (Win32Platform.WindowsVersion < WinUiCompositionShared.MinHostBackdropVersion)