Dear Samsung Member,
Greetings from Samsung Customer Support!
As we have checked, your Galaxy Note 9 smartphone should have received Android Q update in the month of January this year. If you did not receive notification for the same, kindly try to update the software of the device by following path: Settings> Software update> Download and install> Checking for software update> Software update available> Download> Downloading updates> Install now
If the issue remains unresolved, kindly send an error report as soon as you experience the issue(preferably within 15 mins in order for us to get the data that we need) using path: Samsung member app > Get Help > Send Feedback > Error Report
Thank you for writing to Samsung.
Samsung Customer Support