It’s not really a dark pattern because they’re not tricking you into accepting or coercing more than is acceptable into doing so, they’re just not allowing you to decline. Which means if not accepting cookies is a dealbreaker for you, no problem, just: move along.
Dark pattern is a term normally used for legal, but immoral user experience.
In this case legality is questionable as they redirect you to other external sites to manage your "consent" https://optout.aboutads.info (at least from a European GDPR perspective)