Which problem does passing a new object to a memoized child component on every render create?
Passing a new object to a memoized child component on every render bypasses memoization because the object reference changes each time. Even if the contents of the object are identical, a new object reference is created, and shallow comparison (used by React.memo by default) will determine they're different. This causes the memoized component to re-render anyway, defeating the purpose of memoization.