As of a couple weeks ago (the last time I checked) if you are signed in to multiple Google accounts and you cannot accept the non-commercial terms for one of them for AI Studio, the site is horribly broken (the text showing which account they’re asking you to agree to the terms for is blurred, and you can’t switch accounts without agreeing first).
In Google’s very slight defense, Anthropic hasn’t even tried to make a proper sign in system.