> > The default server-side tagging deployment is hosted on an App Engine domain. We recommend that you modify the deployment to use a subdomain of your website instead.
The reason is simple: it creates a denial of service attack on DNS block lists used by things like Pi-Hole and NextDNS. Sure, Google knows that some of the subdomains will be blocked for some block lists... but the vast majority won't be blocked on the vast majority of block lists.
> > The default server-side tagging deployment is hosted on an App Engine domain. We recommend that you modify the deployment to use a subdomain of your website instead.
The reason is simple: it creates a denial of service attack on DNS block lists used by things like Pi-Hole and NextDNS. Sure, Google knows that some of the subdomains will be blocked for some block lists... but the vast majority won't be blocked on the vast majority of block lists.