(PDF) Irish DPA's sweep of thirty-odd websites under its jurisdiction. Lots of good guidance here, but for the point specifically under discussion, ctrl+f "nudge." https://www.dataprotection.ie/sites/default/files/uploads/20... by the DPC on the use of cookies and other tracking technologies.pdf
GDPR enforcement is approximately zero, to my knowledge, so I don't know if there's even really an answer to the question.
For what it's worth, Wikipedia gives the impression no-one really knows. https://en.wikipedia.org/wiki/General_Data_Protection_Regula...