The documentation for creating a CMS element with the Admin SDK does not match the example in shopware/meteor, created by @jleifeld.
Meteor example: https://github.com/shopware/meteor/tree/main/examples/admin-sdk-app/src/frontend
Documentation example: https://developer.shopware.com/docs/guides/plugins/apps/administration/add-cms-element-via-admin-sdk.html
I am not sure if the example in the documentation actually works. On Discord, there is a thread that mentions this.