How can I open parent app from its Siri extension?

What's your use case? If a shortcut supports background execution, you are expected to perform the action in the Intents extension. There are only limited scenarios where a shortcut can launch the main app, such as workouts and media playback.

If background execution of your intent isn't appropriate for your use case, then you can disable background execution in the intents definition file, and handle the shortcut in the main app always, by implementing application(_:continue:restorationHandler:)and getting the intent from the interaction property on the NSUserActivity.

If in Siri intention disabled father application background, this will take the initiative to jump to the parent application and perform application: continueUserActivity: restorationHandler: method? If you can tell me how to disable the parent application background execution, thank you

There is a checkbox in the Intent Definition editor labeled "Supports background execution."