See Is assignment an operator in Python? The answer states:
An assignment is always a statement in Python.
Now, see this link of Assignment Statements. In that, see the Note section (emphasis mine):
Note: If the object is a class instance and the attribute reference occurs on both sides of the assignment operator, the right-hand side expression, a.x can access either an instance attribute or (if no instance attribute exists) a class attribute.
Here the term "assignment operator" is used. Now, the list of operators in the official documentation of Python does not contain an assignment operator, but =
is contained in the Delimiters section.
Is assignment an operator, a statement, or a delimiter?