As I understand it, it is the position of several DPAs that denial of access entirely (i.e. "consent or pay") could contravene the "freely given" requirement of GDPR in most cases, though this has thus far not been tested in court.

(see e.g. https://iapp.org/news/a/cjeu-clarifies-cookie-consent-requir... https://www.edpb.europa.eu/news/edpb-consent-or-pay-models-s... )