I keep seeing Basic Mode and Advanced Mode mentioned in Google guides. Which one controls whether Google code loads before consent?
In broad terms, Basic Mode holds Google tags until the relevant consent is granted. Advanced Mode can load Google tags with denied defaults and allow limited cookieless pings before consent. Consent Mode signals describe consent to Google; they are not the same thing as OptinStack's physical blocking of scripts, iframes, cookies, and storage.
Choose the implementation with your measurement and legal requirements in mind, then verify both the Google signals and actual browser behavior. OptinStack must still load before Google tags so the default state is available early.
Documentation: Google Consent Mode v2 and Basic vs Advanced Google Consent Mode.