Oh, my mistake, I thought this review was on a different plugin of ours for contact forms and there is an option to include additional information like IP.
But the review you posted is actually for “Subscribe to Comments Reloaded” plugin which does not include IP information in the notifications.
The notification message can be changed in WP admin > StCR > Notifications. It’s the “Notification Message” option.
The only information shown about the author is the author’s name.
So I’m not entirely sure what happened here. Do you have email logging (such as WP Mail Logging) to check the emails the subscribers received? Can you confirm that the IP address is shown in there?