BUG: Fix tz-aware comparison in plot() causing failures when timeseries begins at DST boundary

pandas/plotting/_matplotlib/timeseries.py

@@ -251,7 +251,14 @@ def use_dynamic_x(ax: Axes, index: Index) -> bool:
             return index[:1].is_normalized
         period = Period(index[0], freq_str)
         assert isinstance(period, Period)
-        return period.to_timestamp().tz_localize(index.tz) == index[0]
+        if index.tz is not None:
+            # Compare naive local times directly
+            period_naive = period.to_timestamp()
+            index_naive = index[0].tz_localize(None)  # Strips tz, keeps local time
+            return period_naive == index_naive
+        else:
+            return period.to_timestamp() == index[0]
+
     return True