I did forward your concern to the folks responsible for the web site and GDPR compliance - which I know they take very seriously.
From a personal opinion standpoint - while I'm sure there is some clarification to be made on the description, things like " ... provided you have not opted out of such data processing." could have been written " ... provided you have opted into such data processing." Neither says what the default is (the way I read it), just that there is an option.
The EU web site that you point to (for making a complaint), has options for "opt-in" and "opt-in less" (their words are "Accept All Cookies" or "Accept Only Essential Cookies"); there is no opt-out there either. Who is to say which are "essential"? On their cookie description page https://ec.europa.eu/info/cookies_en (which is actually pretty good, and more detailed than most), they don't say which are essential and what are not.... so still have no idea what I'm agreeing to...
Not saying that the ADI site is compliant or not (I only know that lots of folks worked on it and spent a lot of time on it), also acknowledge there are always room for improvements - which may or may not happen (Again - not on that team) - only that's its hard to communicate some of these things sometimes...