When doing/reviewing the collecting of cookies the platform sets I found an option to disable some of the ones google seems to set when using their domain to get the recaptcha api scripts.
https://developers.google.com/recaptcha/docs/faq#does-recaptcha-use-cookies
reCAPTCHA sets a necessary cookie (_GRECAPTCHA) when executed for the purpose of providing its risk analysis. If you prefer to not use the www.google.com domain which may have other cookies set, you can use www.recaptcha.net instead
AC
- UI is using recaptcha.net instead of google.com
- Mediawiki Special:CreateAccount seems to already use recaptcha.net and therefor doesn't set the tracking cookies