Haven't been able to find much info so far and though this would be a good place to ask...
Two aspects to this question:
- Is there any research into the rates of Accepting all cookies via a GDPR compliant banner (and this could also include the rates of choosing to customise the cookies you accept, as well as users who do not engage with the banner at all)
- Is there any related research about compliant UI practices that encourage acceptance, and the extent to which this makes a difference.
Hope there is some solid data out there.