ENH: Improve warning stacklevel

changelog/12564.bugfix.rst

@@ -0,0 +1 @@
+Fix the ``stacklevel`` used when warning about marks used on fixtures.

src/_pytest/fixtures.py

@@ -1192,7 +1192,7 @@ class FixtureFunctionMarker:
             )
 
         if hasattr(function, "pytestmark"):
-            warnings.warn(MARKED_FIXTURE, stacklevel=2)
+            warnings.warn(MARKED_FIXTURE, stacklevel=4)
 
         function = wrap_function_to_error_out_if_called_directly(function, self)
 

testing/deprecated_test.py

@@ -185,6 +185,8 @@ def test_fixture_disallow_on_marked_functions():
     # from applying @fixture twice
     # ValueError("fixture is being applied more than once to the same function")
     assert len(record) == 1
+    # should point to this file
+    assert record[0].filename == __file__
 
 
 def test_fixture_disallow_marks_on_fixtures():