Limits of Material-UI Autocomplete freeSolo prop regarding built-in validation

When using the Material‑UI Autocomplete component with freeSolo set to true, developers can enter arbitrary strings that are not part of the predefined options list. The current documentation states that the component does not perform any automatic validation or transformation of this free‑form input, leaving validation entirely to the application.

The goal is to clarify whether Material‑UI should provide an optional validation mechanism for freeSolo mode, considering backward compatibility, accessibility impact, and performance overhead.

What validation behavior would be most intuitive for developers who need to ensure the entered value matches an option or conforms to a custom rule? How would an optional validation prop interact with existing props such as isOptionEqualToValue and filterOptions? Should validation be opt‑in, or could a sensible default be introduced without breaking existing implementations?