diff --git a/src/_pytest/warnings.py b/src/_pytest/warnings.py
index 986343fd3..0b67bd8f1 100644
--- a/src/_pytest/warnings.py
+++ b/src/_pytest/warnings.py
@@ -85,6 +85,7 @@ def catch_warnings_for_item(config, ihook, item):
                     filters_configured = True
 
         if not filters_configured:
+            # if user is not explicitly configuring warning filters, show deprecation warnings by default (#2908)
             warnings.filterwarnings("always", category=DeprecationWarning)
             warnings.filterwarnings("always", category=PendingDeprecationWarning)