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Reproducible Example

ser = pd.Series(["2016-01-01"], dtype="date32[pyarrow]")
ser2 = ser.astype("timestamp[ns][pyarrow]")
ser3 = ser.astype("datetime64[ns]")
dti = pd.Index(ser3)
dti.get_loc(ser[0]) # raises KeyError
dti.get_indexer(ser.values) # -1s
dti.get_indexer(ser.values.astype(object)) # 0s; inconsistent

Issue Description

DatetimeIndex.get_indexer has a special case (actually in Index._maybe_downcast_for_indexing) for sequences of date objects that is inconsistent with both scalar treatment and comparison op behavior. This was mostly benign before the existence of a date dtype, but now has the potential to cause problems. The special case should be deprecated.

Expected Behavior

NA

Installed Versions