Updated with reviewer comments

Author: arthurlw

pandas/_libs/tslibs/offsets.pyx

@@ -285,7 +285,8 @@ cdef _determine_offset(kwds):
     if not kwds:
         from dateutil.relativedelta import relativedelta
 
-        # GH 45643/45890: (historically) defaults to 1 day
+        # GH 45643, 45890: (historically) defaults to 1 day
+        # GH 61870: changed from timedelta to relativedelta
         return relativedelta(days=1), True
 
     if "millisecond" in kwds:

pandas/tests/tseries/offsets/test_offsets.py

@@ -9,6 +9,7 @@
     timedelta,
 )
 
+from dateutil.relativedelta import relativedelta
 import numpy as np
 import pytest
 
@@ -1095,9 +1096,7 @@ def test_dateoffset_misc():
 
 @pytest.mark.parametrize("n", [-1, 1, 3])
 def test_construct_int_arg_no_kwargs_assumed_days(n):
-    from dateutil.relativedelta import relativedelta
-
-    # GH 45890, 45643
+    # GH 45643, 45890, 61870
     offset = DateOffset(n)
     assert offset._offset == relativedelta(days=1)
     result = Timestamp(2022, 1, 2) + offset