diff --git a/scalafmt-tests/src/test/resources/scala3/OptionalBraces.stat b/scalafmt-tests/src/test/resources/scala3/OptionalBraces.stat
index 3eb8d3c2d0..5cd6937a05 100644
--- a/scalafmt-tests/src/test/resources/scala3/OptionalBraces.stat
+++ b/scalafmt-tests/src/test/resources/scala3/OptionalBraces.stat
@@ -5160,3 +5160,23 @@ object a:
       def slice(offset: Int, length: Int) =
         api.search(query, From(offset), Size(length))
    .mapFutureList
+<<< #3623 beforeCurlyLambdaParams
+newlines.beforeCurlyLambdaParams = true
+===
+object a:
+  List(1, 2, 3) map: x =>
+    x + 1
+>>>
+object a:
+   List(1, 2, 3) map:
+      x => x + 1
+<<< #3623 !beforeCurlyLambdaParams
+newlines.beforeCurlyLambdaParams = false
+===
+object a:
+  List(1, 2, 3) map: x =>
+    x + 1
+>>>
+object a:
+   List(1, 2, 3) map:
+      x => x + 1
diff --git a/scalafmt-tests/src/test/resources/scala3/OptionalBraces_fold.stat b/scalafmt-tests/src/test/resources/scala3/OptionalBraces_fold.stat
index 983e7c971f..423b71e2a4 100644
--- a/scalafmt-tests/src/test/resources/scala3/OptionalBraces_fold.stat
+++ b/scalafmt-tests/src/test/resources/scala3/OptionalBraces_fold.stat
@@ -4927,3 +4927,23 @@ object a:
       def slice(offset: Int, length: Int) = api
         .search(query, From(offset), Size(length))
    .mapFutureList
+<<< #3623 beforeCurlyLambdaParams
+newlines.beforeCurlyLambdaParams = true
+===
+object a:
+  List(1, 2, 3) map: x =>
+    x + 1
+>>>
+object a:
+   List(1, 2, 3) map:
+      x => x + 1
+<<< #3623 !beforeCurlyLambdaParams
+newlines.beforeCurlyLambdaParams = false
+===
+object a:
+  List(1, 2, 3) map: x =>
+    x + 1
+>>>
+object a:
+   List(1, 2, 3) map:
+      x => x + 1
diff --git a/scalafmt-tests/src/test/resources/scala3/OptionalBraces_keep.stat b/scalafmt-tests/src/test/resources/scala3/OptionalBraces_keep.stat
index ce7f99b3fc..40fa232797 100644
--- a/scalafmt-tests/src/test/resources/scala3/OptionalBraces_keep.stat
+++ b/scalafmt-tests/src/test/resources/scala3/OptionalBraces_keep.stat
@@ -5194,3 +5194,25 @@ object a:
       def slice(offset: Int, length: Int) =
         api.search(query, From(offset), Size(length))
    .mapFutureList
+<<< #3623 beforeCurlyLambdaParams
+newlines.beforeCurlyLambdaParams = true
+===
+object a:
+  List(1, 2, 3) map: x =>
+    x + 1
+>>>
+object a:
+   List(1, 2, 3) map:
+      x =>
+        x + 1
+<<< #3623 !beforeCurlyLambdaParams
+newlines.beforeCurlyLambdaParams = false
+===
+object a:
+  List(1, 2, 3) map: x =>
+    x + 1
+>>>
+object a:
+   List(1, 2, 3) map:
+      x =>
+        x + 1
diff --git a/scalafmt-tests/src/test/resources/scala3/OptionalBraces_unfold.stat b/scalafmt-tests/src/test/resources/scala3/OptionalBraces_unfold.stat
index 15abc187a8..4622a2e4e4 100644
--- a/scalafmt-tests/src/test/resources/scala3/OptionalBraces_unfold.stat
+++ b/scalafmt-tests/src/test/resources/scala3/OptionalBraces_unfold.stat
@@ -5326,3 +5326,23 @@ object a:
       def slice(offset: Int, length: Int) = api
         .search(query, From(offset), Size(length))
    .mapFutureList
+<<< #3623 beforeCurlyLambdaParams
+newlines.beforeCurlyLambdaParams = true
+===
+object a:
+  List(1, 2, 3) map: x =>
+    x + 1
+>>>
+object a:
+   List(1, 2, 3) map:
+      x => x + 1
+<<< #3623 !beforeCurlyLambdaParams
+newlines.beforeCurlyLambdaParams = false
+===
+object a:
+  List(1, 2, 3) map: x =>
+    x + 1
+>>>
+object a:
+   List(1, 2, 3) map:
+      x => x + 1