From ico.org.uk: “ It is important to note that opinions and inferences are also personal data, maybe special category data, if they directly or indirectly relate to that individual”

From gdpr-info.eu: “ Subjective information such as opinions, judgements or estimates can be personal data.”

So yes. HN is in violation of the GDPR. I had already filed a complaint about this policy at my local GDPR authority.