GDPR doesn't dictate anything about styling or anything, it just says you have to ask for consent, you're not allowed to bundle consent with anything else (eg you can't say that I have to give consent for me to be able to use the site) and IIRC it does even have a clause about consent having to be asked for in a clear understandable form.
I'm pretty sure that everyone doing our (b) is not compliant at all. The problem is that GDPR isn't being enforced very well.
> GDPR really should have dictated "agree" and "disagree" be of equal visual weight and button styling and dictated disagreeing to be a 1-click action.
It does mandate something to that effect: the user should not have to spend more effort to disagree than to agree.
(b) many people make the disagree button small, hard to see, or require clicking through multiple screens to get to
GDPR really should have dictated "agree" and "disagree" be of equal visual weight and button styling and dictated disagreeing to be a 1-click action.