keras/src/layers/core/lambda_layer.py/Lambda/_raise_for_lambda_deserialization
class Lambda:    def _raise_for_lambda_deserialization(arg_name, safe_mode):
        if safe_mode:
            raise ValueError(
                "The `{arg_name}` of this `Lambda` layer is a Python lambda. "
                "Deserializing it is unsafe. If you trust the source of the "
                "config artifact, you can override this error "
                "by passing `safe_mode=False` "
                "to `from_config()`, or calling "
                "`keras.config.enable_unsafe_deserialization()."
            )