Please use [url/@type] from nms:trackingLogRcp with value = optout in your Query activity.
That is for the unsubscribe link in a delivery that leads either to directly set nms:recipient.@blacklist to 1, or per blacklist per channel, or nly unsubscribe for a dedicated service (and so subHisto data) if you define a webApp for questioning about unsubscribe reasons or unsubscription from specific services.
But there is another use case, it is when the contact unsubscribes by using the client mail functionality instead the unsubscribe link. So the feedback_loop process sets the recipient.blacklist automatically.