def normalize(
            cls,
            config: Any,
            strict: bool = True,
        ):
            """
            Perform validations that require access to to the raw config.
            """
            if strict and isinstance(config, dict):
                # Subtasks may not declare certain options
                for subtask_def in config.get("switch", tuple()):
                    for banned_option in SUBTASK_OPTIONS_BLOCKLIST:
                        if banned_option in subtask_def:
                            if "case" not in subtask_def:
                                raise ConfigValidationError(
                                    "Default case includes incompatible option "
                                    f"{banned_option!r}"
                                )
                            raise ConfigValidationError(
                                f"Case {subtask_def.get('case')!r} includes "
                                f"incompatible option {banned_option!r}"
                            )

            return super().normalize(config, strict)

            Perform validations that require access to to the raw config.
            
poethepoet/task/switch.py