Ok but for any major site cookie consent needs to be associated with user, so I guess can't making use of localStorage for that..

It uses localStorage to store the consent, that falls under essential needs by GDPR

do you mean fails or falls? At any rate if you have a user that can log in on your site you can't assume they are always using the same computer and thus can't use localStorage for that kind of thing, also if someone does not destroy their session when using a public computer and agrees to tracking everything the next person who comes to site on public computer has now agreed to tracking everything.