Avoid post action flashing

[missile-developer]

I did implementing test on both useFetcher and useSubmit with navigate: false. However in my scenario it still got some flashy blink when it trigger. I really new here.

Please help me solve this or some best practice I should follow to post action without any redirect change

// form.tsx

fetcher.submit(formData, {
          action: '/hidden/world',
          method: 'post',
          encType: 'multipart/form-data'
        })

// page.tsx

export async function action({ request }: ActionFunctionArgs) {
  if (true) {
    return redirect('/hidden/world')
  } else {
    const cookieHeader = await updateSession(request)

    return json(null, {
      headers: {
        'Set-Cookie': cookieHeader
      }
    })
  }
}