Microsoftccalvarez So you can definitely still accomplish this.
services.AddSpaStaticFiles(options => options.RootPath = "client-app/dist");
This tells the service to serve the compiled application from the client-app/dist folder.
When you run locally in dev, you have a reverse proxy from your service to the hot-reloaded server that npm spins up (which is great for development, but inefficient for a deployed service).
You'll want to publish your Vue project to the client-app/dist (or whatever folder you prefer). That will compile your project, do minification and all that good stuff, and then your server will serve those files directly instead of through the reverse proxy. If you look at the csproj file above, it should already be doing that step for you. Just make sure that you do an actual publish and then wrap your middleware in a environment check like he has above:
if (env.IsDevelopment())
{
// Launch development server for Vue.js
spa.UseVueDevelopmentServer();
}