DOC: Clarify deterministic sorting behavior for ties

pandas/core/base.py

@@ -997,8 +997,12 @@ def value_counts(
             when False.
 
             .. versionchanged:: 3.0.0
-
                 Prior to 3.0.0, the sort was unstable.
+
+            .. versionchanged:: 2.2.0
+                The default sort kind 'quicksort' is deterministic,
+                i.e. it produces the same result for the same input on each run.
+
         ascending : bool, default False
             Sort in ascending order.
         bins : int, optional

pandas/core/frame.py

@@ -7337,6 +7337,11 @@ def sort_values(
              information. `mergesort` and `stable` are the only stable algorithms. For
              DataFrames, this option is only applied when sorting on a single
              column or label.
+
+             .. versionchanged:: 2.2.0
+
+                 The default sort kind 'quicksort' is deterministic,
+                 i.e. it produces the same result for the same input on each run.
         na_position : {'first', 'last'}, default 'last'
              Puts NaNs at the beginning if `first`; `last` puts NaNs at the
              end.
@@ -7657,6 +7662,11 @@ def sort_index(
             information. `mergesort` and `stable` are the only stable algorithms. For
             DataFrames, this option is only applied when sorting on a single
             column or label.
+
+            .. versionchanged:: 2.2.0
+
+                The default sort kind 'quicksort' is deterministic,
+                i.e. it produces the same result for the same input on each run.
         na_position : {'first', 'last'}, default 'last'
             Puts NaNs at the beginning if `first`; `last` puts NaNs at the end.
             Not implemented for MultiIndex.

pandas/core/series.py

@@ -3500,6 +3500,11 @@ def sort_values(
         kind : {'quicksort', 'mergesort', 'heapsort', 'stable'}, default 'quicksort'
             Choice of sorting algorithm. See also :func:`numpy.sort` for more
             information. 'mergesort' and 'stable' are the only stable  algorithms.
+
+            .. versionchanged:: 2.2.0
+                The default sort kind 'quicksort' is deterministic,
+                i.e. it produces the same result for the same input on each run.
+
         na_position : {'first' or 'last'}, default 'last'
             Argument 'first' puts NaNs at the beginning, 'last' puts NaNs at
             the end.
@@ -3746,6 +3751,11 @@ def sort_index(
             information. 'mergesort' and 'stable' are the only stable algorithms. For
             DataFrames, this option is only applied when sorting on a single
             column or label.
+
+            .. versionchanged:: 2.2.0
+
+                The default sort kind 'quicksort' is deterministic,
+                i.e. it produces the same result for the same input on each run.
         na_position : {'first', 'last'}, default 'last'
             If 'first' puts NaNs at the beginning, 'last' puts NaNs at the end.
             Not implemented for MultiIndex.