diff --git a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
index 177cfa794a..f1b96af8ea 100644
--- a/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
+++ b/scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala
@@ -1368,16 +1368,18 @@ class Router(formatOps: FormatOps) {
           )
         }
         bopSplits.getOrElse {
-          val penalizeNewlines =
-            PenalizeAllNewlines(expire, Constants.BracketPenalty)
+          def penalizeNewlines(extra: Int)(implicit fileLine: FileLine) =
+            PenalizeAllNewlines(expire, Constants.BracketPenalty + extra)
           val indent = style.indent.getDefnSite(leftOwner)
+          val nlPenalty = 2 + treeDepth(returnType)
           Seq(
             Split(style.newlines.keepBreak(hasBreak()), 0)(sameLineSplit)
-              .withPolicy(penalizeNewlines),
+              .withPolicy(penalizeNewlines(0)),
             // Spark style guide allows this:
             // https://github.com/databricks/scala-style-guide#indent
-            Split(Newline, Constants.SparkColonNewline)
-              .withIndent(indent, expire, After).withPolicy(penalizeNewlines),
+            Split(Newline, Constants.SparkColonNewline + nlPenalty)
+              .withIndent(indent, expire, After)
+              .withPolicy(penalizeNewlines(nlPenalty)),
           )
         }
       case FormatToken(_: T.Colon, _, ColonDeclTpeLeft(returnType))
diff --git a/scalafmt-tests/shared/src/test/resources/newlines/source_classic.stat b/scalafmt-tests/shared/src/test/resources/newlines/source_classic.stat
index 94c75e8d5d..a422ded05a 100644
--- a/scalafmt-tests/shared/src/test/resources/newlines/source_classic.stat
+++ b/scalafmt-tests/shared/src/test/resources/newlines/source_classic.stat
@@ -9856,17 +9856,17 @@ object Multipart {
   }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       //
--  ): Flow[MultipartFormData.Part[
--    Source_ByteString
--  ], ByteString, NotUsed] = {
-+  )
-+      : Flow[MultipartFormData.Part[
-+        Source_ByteString
-+      ], ByteString, NotUsed] = {
-     //
+object Multipart {
+  def format(
+      //
+  ): Flow[
+    MultipartFormData.Part[Source_ByteString],
+    ByteString,
+    NotUsed
+  ] = {
+    //
+  }
+}
 <<< #4133 overflowing complex result type 2
 preset = default
 maxColumn = 80
@@ -9880,14 +9880,16 @@ object Multipart {
     }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       //
--  ): GraphStage[FlowShape[MultipartFormData.Part[
--    Source[ByteString, _]
--  ], Source[ByteString, Any]]] =
-+  )
-+      : GraphStage[FlowShape[MultipartFormData.Part[
-+        Source[ByteString, _]
-+      ], Source[ByteString, Any]]] =
-     new GraphStage[FlowShape[MultipartFormData.Part[
+object Multipart {
+  private def streamed(
+      //
+  ): GraphStage[FlowShape[
+    MultipartFormData.Part[Source[ByteString, _]],
+    Source[ByteString, Any]
+  ]] =
+    new GraphStage[FlowShape[MultipartFormData.Part[
+      Source[ByteString, _]
+    ], Source[ByteString, Any]]] {
+      //
+    }
+}
diff --git a/scalafmt-tests/shared/src/test/resources/newlines/source_fold.stat b/scalafmt-tests/shared/src/test/resources/newlines/source_fold.stat
index af9ca3b805..70eb8b197a 100644
--- a/scalafmt-tests/shared/src/test/resources/newlines/source_fold.stat
+++ b/scalafmt-tests/shared/src/test/resources/newlines/source_fold.stat
@@ -9252,17 +9252,17 @@ object Multipart {
   }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       //
--  ): Flow[MultipartFormData.Part[
--    Source_ByteString
--  ], ByteString, NotUsed] = {
-+  )
-+      : Flow[MultipartFormData.Part[
-+        Source_ByteString
-+      ], ByteString, NotUsed] = {
-     //
+object Multipart {
+  def format(
+      //
+  ): Flow[
+    MultipartFormData.Part[Source_ByteString],
+    ByteString,
+    NotUsed
+  ] = {
+    //
+  }
+}
 <<< #4133 overflowing complex result type 2
 preset = default
 maxColumn = 80
@@ -9276,14 +9276,16 @@ object Multipart {
     }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       //
--  ): GraphStage[FlowShape[MultipartFormData.Part[
--    Source[ByteString, _]
--  ], Source[ByteString, Any]]] =
-+  )
-+      : GraphStage[FlowShape[MultipartFormData.Part[
-+        Source[ByteString, _]
-+      ], Source[ByteString, Any]]] =
-     new GraphStage[FlowShape[MultipartFormData.Part[
+object Multipart {
+  private def streamed(
+      //
+  ): GraphStage[FlowShape[
+    MultipartFormData.Part[Source[ByteString, _]],
+    Source[ByteString, Any]
+  ]] =
+    new GraphStage[FlowShape[MultipartFormData.Part[
+      Source[ByteString, _]
+    ], Source[ByteString, Any]]] {
+      //
+    }
+}
diff --git a/scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat b/scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat
index eb467df457..77e2f2f3c4 100644
--- a/scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat
+++ b/scalafmt-tests/shared/src/test/resources/newlines/source_keep.stat
@@ -9653,17 +9653,17 @@ object Multipart {
   }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       //
--  ): Flow[MultipartFormData.Part[
--    Source_ByteString
--  ], ByteString, NotUsed] = {
-+  )
-+      : Flow[MultipartFormData.Part[
-+        Source_ByteString
-+      ], ByteString, NotUsed] = {
-     //
+object Multipart {
+  def format(
+      //
+  ): Flow[
+    MultipartFormData.Part[Source_ByteString],
+    ByteString,
+    NotUsed
+  ] = {
+    //
+  }
+}
 <<< #4133 overflowing complex result type 2
 preset = default
 maxColumn = 80
@@ -9677,14 +9677,16 @@ object Multipart {
     }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       //
--  ): GraphStage[FlowShape[MultipartFormData.Part[
--    Source[ByteString, _]
--  ], Source[ByteString, Any]]] =
-+  )
-+      : GraphStage[FlowShape[MultipartFormData.Part[
-+        Source[ByteString, _]
-+      ], Source[ByteString, Any]]] =
-     new GraphStage[FlowShape[MultipartFormData.Part[
+object Multipart {
+  private def streamed(
+      //
+  ): GraphStage[FlowShape[
+    MultipartFormData.Part[Source[ByteString, _]],
+    Source[ByteString, Any]
+  ]] =
+    new GraphStage[FlowShape[MultipartFormData.Part[
+      Source[ByteString, _]
+    ], Source[ByteString, Any]]] {
+      //
+    }
+}
diff --git a/scalafmt-tests/shared/src/test/resources/newlines/source_unfold.stat b/scalafmt-tests/shared/src/test/resources/newlines/source_unfold.stat
index faf9230e32..63a809b573 100644
--- a/scalafmt-tests/shared/src/test/resources/newlines/source_unfold.stat
+++ b/scalafmt-tests/shared/src/test/resources/newlines/source_unfold.stat
@@ -9949,17 +9949,17 @@ object Multipart {
   }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       //
--  ): Flow[MultipartFormData.Part[
--    Source_ByteString
--  ], ByteString, NotUsed] = {
-+  )
-+      : Flow[MultipartFormData.Part[
-+        Source_ByteString
-+      ], ByteString, NotUsed] = {
-     //
+object Multipart {
+  def format(
+      //
+  ): Flow[
+    MultipartFormData.Part[Source_ByteString],
+    ByteString,
+    NotUsed
+  ] = {
+    //
+  }
+}
 <<< #4133 overflowing complex result type 2
 preset = default
 maxColumn = 80
@@ -9973,14 +9973,16 @@ object Multipart {
     }
 }
 >>>
-Idempotency violated
-=> Diff (- obtained, + expected)
-       //
--  ): GraphStage[FlowShape[MultipartFormData.Part[
--    Source[ByteString, _]
--  ], Source[ByteString, Any]]] =
-+  )
-+      : GraphStage[FlowShape[MultipartFormData.Part[
-+        Source[ByteString, _]
-+      ], Source[ByteString, Any]]] =
-     new GraphStage[FlowShape[MultipartFormData.Part[
+object Multipart {
+  private def streamed(
+      //
+  ): GraphStage[FlowShape[
+    MultipartFormData.Part[Source[ByteString, _]],
+    Source[ByteString, Any]
+  ]] =
+    new GraphStage[FlowShape[MultipartFormData.Part[
+      Source[ByteString, _]
+    ], Source[ByteString, Any]]] {
+      //
+    }
+}