Fix a line and add whatsnew

Author: snitish

doc/source/whatsnew/v3.0.0.rst

@@ -631,6 +631,7 @@ Datetimelike
 - Bug in :func:`date_range` where using a negative frequency value would not include all points between the start and end values (:issue:`56147`)
 - Bug in :func:`tseries.api.guess_datetime_format` would fail to infer time format when "%Y" == "%H%M" (:issue:`57452`)
 - Bug in :func:`tseries.frequencies.to_offset` would fail to parse frequency strings starting with "LWOM" (:issue:`59218`)
+- Bug in :meth:`DataFrame.min` and :meth:`DataFrame.max` casting ``datetime64`` and ``timedelta64`` columns to ``float64`` and losing precision (:issue:`60850`)
 - Bug in :meth:`Dataframe.agg` with df with missing values resulting in IndexError (:issue:`58810`)
 - Bug in :meth:`DatetimeIndex.is_year_start` and :meth:`DatetimeIndex.is_quarter_start` does not raise on Custom business days frequencies bigger then "1C" (:issue:`58664`)
 - Bug in :meth:`DatetimeIndex.is_year_start` and :meth:`DatetimeIndex.is_quarter_start` returning ``False`` on double-digit frequencies (:issue:`58523`)

pandas/core/nanops.py

@@ -1527,7 +1527,7 @@ def _maybe_null_out(
             if datetimelike:
                 # GH#60646 For datetimelike, no need to cast to float
                 result[null_mask] = iNaT
-            if is_numeric_dtype(result):
+            elif is_numeric_dtype(result):
                 if np.iscomplexobj(result):
                     result = result.astype("c16")
                 elif not is_float_dtype(result):