doesn't this affect auth on, like, every website you visit? (genuinely curious)

You don't need a cookie banner for auth cookies. You only need consent (aka the banner) for 3rd party cookies and tracking cookies.

Cookies that are strictly necessary for the functionality (auth, user preferences, shopping cart, etc...) of the site don't need user consent.

cookies, newsletter popups, sign-in popups, product tours, soft paywalls, etc.