More detailed comment.

pyqtgraph/graphicsItems/CurvePoint.py

@@ -91,7 +91,9 @@ class CurvePoint(GraphicsObject):
         pass
     
     def makeAnimation(self, prop='position', start=0.0, end=1.0, duration=10000, loop=1):
-        # automatic encoding when QByteString expected was removed in PyQt v5.5
+        # In Python 3, a bytes object needs to be used as a property name in
+        # QPropertyAnimation. PyQt stopped automatically encoding a str when a
+        # QByteArray was expected in v5.5 (see qbytearray.sip).
         if not isinstance(prop, bytes):
             prop = prop.encode('latin-1')
         anim = QtCore.QPropertyAnimation(self, prop)