Hey there!
In the storage log, whatever controller, unzip the log, find the directory xxx\msg_other\Other\.
Get the protocol_info_*.zip file; * is the date you collected the log.
Open the nas_smb_info.log file; for SMB1, search get_smb_stat and check the Details Of Commands results - for example:
If the result is not 0, it means some clients have used the SMB1 protocol before.
For SMB2, search get_smb2_stat, check the Command Detail Statistics.
If the result is not 0, it means some clients have used the SMB2 protocol before.
Note that the result only records the result from the last controller restart time.