diff --git a/lib/ui/compositing.dart b/lib/ui/compositing.dart
index 4f9e66fe257dd..5ad4693597d5d 100644
--- a/lib/ui/compositing.dart
+++ b/lib/ui/compositing.dart
@@ -283,7 +283,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   /// {@endtemplate}
   ///
   /// See [pop] for details about the operation stack.
-  TransformEngineLayer? pushTransform(
+  TransformEngineLayer pushTransform(
     Float64List matrix4, {
     TransformEngineLayer? oldLayer,
   }) {
@@ -308,7 +308,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   /// {@macro dart.ui.sceneBuilder.oldLayerVsRetained}
   ///
   /// See [pop] for details about the operation stack.
-  OffsetEngineLayer? pushOffset(
+  OffsetEngineLayer pushOffset(
     double dx,
     double dy, {
     OffsetEngineLayer? oldLayer,
@@ -334,7 +334,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   ///
   /// See [pop] for details about the operation stack, and [Clip] for different clip modes.
   /// By default, the clip will be anti-aliased (clip = [Clip.antiAlias]).
-  ClipRectEngineLayer? pushClipRect(
+  ClipRectEngineLayer pushClipRect(
     Rect rect, {
     Clip clipBehavior = Clip.antiAlias,
     ClipRectEngineLayer? oldLayer,
@@ -363,7 +363,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   ///
   /// See [pop] for details about the operation stack, and [Clip] for different clip modes.
   /// By default, the clip will be anti-aliased (clip = [Clip.antiAlias]).
-  ClipRRectEngineLayer? pushClipRRect(
+  ClipRRectEngineLayer pushClipRRect(
     RRect rrect, {
     Clip clipBehavior = Clip.antiAlias,
     ClipRRectEngineLayer? oldLayer,
@@ -391,7 +391,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   ///
   /// See [pop] for details about the operation stack. See [Clip] for different clip modes.
   /// By default, the clip will be anti-aliased (clip = [Clip.antiAlias]).
-  ClipPathEngineLayer? pushClipPath(
+  ClipPathEngineLayer pushClipPath(
     Path path, {
     Clip clipBehavior = Clip.antiAlias,
     ClipPathEngineLayer? oldLayer,
@@ -421,7 +421,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   /// {@macro dart.ui.sceneBuilder.oldLayerVsRetained}
   ///
   /// See [pop] for details about the operation stack.
-  OpacityEngineLayer? pushOpacity(
+  OpacityEngineLayer pushOpacity(
     int alpha, {
     Offset? offset = Offset.zero,
     OpacityEngineLayer? oldLayer,
@@ -447,7 +447,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   /// {@macro dart.ui.sceneBuilder.oldLayerVsRetained}
   ///
   /// See [pop] for details about the operation stack.
-  ColorFilterEngineLayer? pushColorFilter(
+  ColorFilterEngineLayer pushColorFilter(
     ColorFilter filter, {
     ColorFilterEngineLayer? oldLayer,
   }) {
@@ -475,7 +475,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   /// {@macro dart.ui.sceneBuilder.oldLayerVsRetained}
   ///
   /// See [pop] for details about the operation stack.
-  ImageFilterEngineLayer? pushImageFilter(
+  ImageFilterEngineLayer pushImageFilter(
     ImageFilter filter, {
     ImageFilterEngineLayer? oldLayer,
   }) {
@@ -504,7 +504,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   /// {@macro dart.ui.sceneBuilder.oldLayerVsRetained}
   ///
   /// See [pop] for details about the operation stack.
-  BackdropFilterEngineLayer? pushBackdropFilter(
+  BackdropFilterEngineLayer pushBackdropFilter(
     ImageFilter filter, {
     BlendMode blendMode = BlendMode.srcOver,
     BackdropFilterEngineLayer? oldLayer,
@@ -530,7 +530,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   /// {@macro dart.ui.sceneBuilder.oldLayerVsRetained}
   ///
   /// See [pop] for details about the operation stack.
-  ShaderMaskEngineLayer? pushShaderMask(
+  ShaderMaskEngineLayer pushShaderMask(
     Shader shader,
     Rect maskRect,
     BlendMode blendMode, {
@@ -582,7 +582,7 @@ class SceneBuilder extends NativeFieldWrapperClass2 {
   /// {@macro dart.ui.sceneBuilder.oldLayerVsRetained}
   ///
   /// See [pop] for details about the operation stack, and [Clip] for different clip modes.
-  PhysicalShapeEngineLayer? pushPhysicalShape({
+  PhysicalShapeEngineLayer pushPhysicalShape({
     required Path path,
     required double elevation,
     required Color color,
diff --git a/lib/web_ui/lib/src/engine/canvaskit/layer_scene_builder.dart b/lib/web_ui/lib/src/engine/canvaskit/layer_scene_builder.dart
index e022b0ba8de42..1a1c950b58b94 100644
--- a/lib/web_ui/lib/src/engine/canvaskit/layer_scene_builder.dart
+++ b/lib/web_ui/lib/src/engine/canvaskit/layer_scene_builder.dart
@@ -98,7 +98,7 @@ class LayerSceneBuilder implements ui.SceneBuilder {
   }
 
   @override
-  BackdropFilterEngineLayer? pushBackdropFilter(
+  BackdropFilterEngineLayer pushBackdropFilter(
     ui.ImageFilter filter, {
     ui.BlendMode blendMode = ui.BlendMode.srcOver,
     ui.EngineLayer? oldLayer,
@@ -110,7 +110,7 @@ class LayerSceneBuilder implements ui.SceneBuilder {
   }
 
   @override
-  ClipPathEngineLayer? pushClipPath(
+  ClipPathEngineLayer pushClipPath(
     ui.Path path, {
     ui.Clip clipBehavior = ui.Clip.antiAlias,
     ui.EngineLayer? oldLayer,
@@ -119,7 +119,7 @@ class LayerSceneBuilder implements ui.SceneBuilder {
   }
 
   @override
-  ClipRRectEngineLayer? pushClipRRect(
+  ClipRRectEngineLayer pushClipRRect(
     ui.RRect rrect, {
     ui.Clip? clipBehavior,
     ui.EngineLayer? oldLayer,
@@ -128,7 +128,7 @@ class LayerSceneBuilder implements ui.SceneBuilder {
   }
 
   @override
-  ClipRectEngineLayer? pushClipRect(
+  ClipRectEngineLayer pushClipRect(
     ui.Rect rect, {
     ui.Clip clipBehavior = ui.Clip.antiAlias,
     ui.EngineLayer? oldLayer,
@@ -137,7 +137,7 @@ class LayerSceneBuilder implements ui.SceneBuilder {
   }
 
   @override
-  ColorFilterEngineLayer? pushColorFilter(
+  ColorFilterEngineLayer pushColorFilter(
     ui.ColorFilter filter, {
     ui.ColorFilterEngineLayer? oldLayer,
   }) {
@@ -145,7 +145,7 @@ class LayerSceneBuilder implements ui.SceneBuilder {
     return pushLayer<ColorFilterEngineLayer>(ColorFilterEngineLayer(filter));
   }
 
-  ImageFilterEngineLayer? pushImageFilter(
+  ImageFilterEngineLayer pushImageFilter(
     ui.ImageFilter filter, {
     ui.ImageFilterEngineLayer? oldLayer,
   }) {
@@ -202,7 +202,7 @@ class LayerSceneBuilder implements ui.SceneBuilder {
   }
 
   @override
-  TransformEngineLayer? pushTransform(
+  TransformEngineLayer pushTransform(
     Float64List matrix4, {
     ui.EngineLayer? oldLayer,
   }) {
diff --git a/lib/web_ui/lib/src/ui/compositing.dart b/lib/web_ui/lib/src/ui/compositing.dart
index 5b84a2240d95d..a177a15f41f84 100644
--- a/lib/web_ui/lib/src/ui/compositing.dart
+++ b/lib/web_ui/lib/src/ui/compositing.dart
@@ -39,56 +39,56 @@ abstract class SceneBuilder {
       return engine.SurfaceSceneBuilder();
     }
   }
-  OffsetEngineLayer? pushOffset(
+  OffsetEngineLayer pushOffset(
     double dx,
     double dy, {
     OffsetEngineLayer? oldLayer,
   });
-  TransformEngineLayer? pushTransform(
+  TransformEngineLayer pushTransform(
     Float64List matrix4, {
     TransformEngineLayer? oldLayer,
   });
-  ClipRectEngineLayer? pushClipRect(
+  ClipRectEngineLayer pushClipRect(
     Rect rect, {
     Clip clipBehavior = Clip.antiAlias,
     ClipRectEngineLayer? oldLayer,
   });
-  ClipRRectEngineLayer? pushClipRRect(
+  ClipRRectEngineLayer pushClipRRect(
     RRect rrect, {
     required Clip clipBehavior,
     ClipRRectEngineLayer? oldLayer,
   });
-  ClipPathEngineLayer? pushClipPath(
+  ClipPathEngineLayer pushClipPath(
     Path path, {
     Clip clipBehavior = Clip.antiAlias,
     ClipPathEngineLayer? oldLayer,
   });
-  OpacityEngineLayer? pushOpacity(
+  OpacityEngineLayer pushOpacity(
     int alpha, {
     Offset offset = Offset.zero,
     OpacityEngineLayer? oldLayer,
   });
-  ColorFilterEngineLayer? pushColorFilter(
+  ColorFilterEngineLayer pushColorFilter(
     ColorFilter filter, {
     ColorFilterEngineLayer? oldLayer,
   });
-  ImageFilterEngineLayer? pushImageFilter(
+  ImageFilterEngineLayer pushImageFilter(
     ImageFilter filter, {
     ImageFilterEngineLayer? oldLayer,
   });
-  BackdropFilterEngineLayer? pushBackdropFilter(
+  BackdropFilterEngineLayer pushBackdropFilter(
     ImageFilter filter, {
     BlendMode blendMode = BlendMode.srcOver,
     BackdropFilterEngineLayer? oldLayer,
   });
-  ShaderMaskEngineLayer? pushShaderMask(
+  ShaderMaskEngineLayer pushShaderMask(
     Shader shader,
     Rect maskRect,
     BlendMode blendMode, {
     ShaderMaskEngineLayer? oldLayer,
     FilterQuality filterQuality = FilterQuality.low,
   });
-  PhysicalShapeEngineLayer? pushPhysicalShape({
+  PhysicalShapeEngineLayer pushPhysicalShape({
     required Path path,
     required double elevation,
     required Color color,