If your scan report contains unclassified cookies, please see Unclassified cookies - how do I classify them manually? for information on why they appear and what can be done to classify them.
In the context of GDPR compliance and if you are using Manual Cookie Blocking Mode do remember to enable 'prior consent' also for those cookies that are unclassified. If you are using Automatic Cookie Blocking mode, please note that the setting of unclassified cookies may rely on the consent given and other cookies set from the same source. In order to ensure correct behavior according to consent and to provide your users with full transparency we urge you to update any unclassified cookies and make this a routine part of your recurring website maintenance.
If you do not know what the purpose of an unclassified cookie is, then you can choose to mark it up as a marketing cookie - which is the most intrusive kind of cookie - just to be on the safe side. See 1. Make sure you have enabled ‘prior consent’ as well as What does ‘prior consent’ mean and how do I implement it?.