Problem: How to split server-sitemap into multiple sitemaps.

Attempt: I have tried limiting it through the next-sitemap config file like this:

/** @type {import('next-sitemap').IConfig} */
module.exports = {
    siteUrl: process.env.SITE_URL || 'https://www.example.com',
    generateRobotsTxt: true,
    exclude: ['/server-sitemap.xml'],
    sitemapSize: 10000,
    robotsTxtOptions: {
        additionalSitemaps: [
            `${process.env.SITE_URL}/server-sitemap.xml`
        ],
        policies: [
            {
                userAgent: '*',
                allow: '/'
            }
        ]
    }
}

But I don't think this works on the sitemaps on /server-sitemap.xml

Does anyone know how to correctly implement this?