Supabase Auth: why set supabaseResponse in setAll() again?

export async function updateSession(request: NextRequest) {
  let supabaseResponse = NextResponse.next({request})
  // With Fluid compute, don't put this client in a global environment
  // variable. Always create a new one on each request.
  const supabase = createServerClient(
    process.env.NEXT_PUBLIC_SUPABASE_URL!,
    process.env.NEXT_PUBLIC_SUPABASE_PUBLISHABLE_KEY!,
    {
      cookies: {
        getAll() {
          return request.cookies.getAll()
        },
        setAll(cookiesToSet) {
          cookiesToSet.forEach(({ name, value }) => request.cookies.set(name, value))
          supabaseResponse = NextResponse.next({request})
          cookiesToSet.forEach(({ name, value, options }) => supabaseResponse.cookies.set(name, value, options))
        },
      },
    }
  )