You are right. I missed something here.

This works

      # Navigate to appointments list
      {:ok, view, _html} = live(conn, ~q"/:locale/user/appointments")

      # Navigate to first appointment
      render_patch(view, ~q"/:locale/user/appointments/123")

      # Wait for async data to load and render
      html1 = render_async(view)

      # Verify first appointment data
      assert html1 =~ "Location One"
      assert html1 =~ "123-456"
      assert html1 =~ "John Doe"

      # Navigate directly to second appointment
      render_patch(view, ~q"/:locale/user/appointments/456")

      # Wait for async data to load and render
      html2 = render_async(view)

      # Verify second appointment data
      assert html2 =~ "Location Two"
      assert html2 =~ "789-012"
      assert html2 =~ "Jane Smith"

      # Ensure first appointment data is no longer present
      refute html2 =~ "Location One"