figured it out, it needed to clear the PreloadStore
So one can edit your default theme or a new component to add this to the JS:
import { apiInitializer } from "discourse/lib/api";
import { setDefaultHomepage } from "discourse/lib/utilities";
import PreloadStore from "discourse/lib/preload-store";
export default apiInitializer((api) => {
setDefaultHomepage("latest?order=created&");
PreloadStore.remove("topic_list");
});
and this CSS to remove the Latest tab:
li.nav-item_latest {
display: none;
}
Wish it could stay on the root homepage url, but that will probably take a plugin.