Are the nextjs docs outdated?

I'm trying to follow their guide for https://nextjs.org/docs/app/building-your-application/authentication after taking a break from last time because the structure was confusing, now for example they use <form action={signup}> in their example, but this throws

Error: Functions cannot be passed directly to Client Components unless you explicitly expose it by marking it with "use server". Or maybe you meant to call this function rather than return it.