diff --git a/lib/matplotlib/animation.py b/lib/matplotlib/animation.py
index 7ff2dd36b5bb..c9d7c03478a3 100644
--- a/lib/matplotlib/animation.py
+++ b/lib/matplotlib/animation.py
@@ -361,12 +361,10 @@ def finish(self):
     def grab_frame(self, **savefig_kwargs):
         # docstring inherited
         _log.debug('MovieWriter.grab_frame: Grabbing frame.')
-        # re-adjust the figure size in case it has been changed by the
-        # user.  We must ensure that every frame is the same size or
-        # the movie will not save correctly.
+        # Readjust the figure size in case it has been changed by the user.
+        # All frames must have the same size to save the movie correctly.
         self.fig.set_size_inches(self._w, self._h)
-        # Tell the figure to save its data to the sink, using the
-        # frame format and dpi.
+        # Save the figure data to the sink, using the frame format and dpi.
         self.fig.savefig(self._frame_sink(), format=self.frame_format,
                          dpi=self.dpi, **savefig_kwargs)
 
@@ -1113,10 +1111,12 @@ def func(current_frame: int, total_frames: int) -> Any
                       "frame size to vary, which is inappropriate for "
                       "animation.")
         # canvas._is_saving = True makes the draw_event animation-starting
-        # callback a no-op.
+        # callback a no-op; canvas.manager = None prevents resizing the GUI
+        # widget (both are likewise done in savefig()).
         with mpl.rc_context({'savefig.bbox': None}), \
              writer.saving(self._fig, filename, dpi), \
-             cbook._setattr_cm(self._fig.canvas, _is_saving=True):
+             cbook._setattr_cm(self._fig.canvas,
+                               _is_saving=True, manager=None):
             for anim in all_anim:
                 anim._init_draw()  # Clear the initial frame
             frame_number = 0