[HiPad Plus] flashed to Android 11 but security patch still on September 2021

Hi, I recently upgraded my HiPad Plus to Android 11 following your instructions. All is fine but Android security update is September 2021 and when I check for system updates the message is “your system is up to date”. Is this correct? How do I get/install a more recent Android 11 security update? Thank you in advance for your answer.