Next.js is not building page as SSG when it should

I am trying to understand why Next.js is building some of my pages as SSG and some of them as Static, when they all are using getStaticProps.

Let's take my 404 page that uses getStaticProps to fetch data from prismic with graphql. It is being rendered as a Static website when in my opinion it should be rendered as SSG (because it uses getStaticProps).

I am doing the EXACT same thing in my 500 page, but with a different graphql query and it is being rendered (in my opinion correctly) as SSG.

Why is that?

404 page:

const NotFound = ({ data: { page } }) => {
    return (
        <div className={'not-found'}>
            <p className={'not-found__description'}>{RichText.asText(page.description)}</p>
        </div>
    );
};

export const getStaticProps = async (context) => {
    const currentLanguage = getCurrentLocale(context);

    const response = await apolloClient.query({
        query: gql`
            query {
            }
        `
    };

    return {
        props: {
            data: {
                page: response
            }
        }
    }
});

export default NotFound;

500 page:

const InternalServerError = ({ data: { page } }) => {
    return (
        <div className={'internal-server-error'}>
             <p className={'internal-server-error__description'}>{RichText.asText(page.description)}</p>
        </div>
    );
};

export const getStaticProps = async (context) => {
    const currentLanguage = getCurrentLocale(context);
    
    const response = await apolloClient.query({
        query: gql`
            query {
            }
        `
    });
    
    return {
        props: {
            data: {
                page: response
            }
        }
    }
};

from Next.js is not building page as SSG when it should