It's probably not a bad idea to remove those devices from Jamf Pro when you release them from Apple School Manager (or Apple Business Manager). The easiest way would be to search for the same list of serial numbers you released in AxM (searching for a series of serial numbers separated by commas e.g. SERIAL1,SERIAL2,SERIAL3 will find all matching devices), then use the 'Action' button to delete them.
If you need to reconcile what you have now, export the list of serials from Apple School Manager, separate computers and mobile devices, and then export lists of managed computers and mobile devices from Jamf Pro and compare the two lists in Numbers (or Excel etc). Those serial numbers in Jamf, but not in Apple School Manager can be deleted using the process described above.