Hello @emgweb,
SiteGround Security plugin provides separate filters that allow you to preview the activity from registered users and to check the list of blocked IP addresses.
You will find all blocked IPs in your WordPress Dashboard -> SG Security-> Activity Log -> Blocked. The IP addresses of the logged-in users can be found under the Registered tab in the same section.
You can also do the same via wp-cli, using the commands below:
wp sg list log-registered
wp sg list log-blocked
As far as I understand, you wish to know if a blocked IP address belongs to a registered user. There is no such filter and you should manually compare the blocked IPs to the most recent IPs logged for a particular registered user.
Best Regards,
Kuzman Stoyanov