Earlier quoted context omitted.
Why do you participate in discussion about the GDPR when you clearly know nothing about it? Of course a "like" or any kind of data that is core to the service doesn't infringe the GDPR. The illegal part is about processing or forwarding personal data of users to third parties, when users haven't agreed to that aspect of the "service". You usually see the distinction between "functional" and "advertising" cookies in t…
I literally work in this field and can tell you that "likes" are regulated under GDPR just like any other personal data. If someone asks us to delete under GDPR, we have to delete these as well.
Being roughly familiar with GDPR, I would be reasonably certain that you could keep a like as long as the identity it's attached to is deleted. Much in the same way as you may see reddit posts that just show a [deleted] user.