A Server-Side GTM container compliments a client-side container, it does not fully replace it.

Some processing happens on the server, but event data must still be sent to the server-side container first. For now, the "standard" deployment of a server-side is that it receives hits directly from the browser, orchestrated by a traditional client-side container. So the client-side script is still there, just less bloated.

The server-side container has built-in facilities for serving up the client-side container script. Meaning that domain-name blocking will not prevent this. DNS-based also has some issues: Server-Side Containers run in App Engine, blocking them basically means blocking anything running on GCP.

and you can host the container: https://developers.google.com/tag-platform/tag-manager/serve...

Current GTM, configured (via the server UI) to inject tracker X:

gtm javascript loads, pulls down the config, injects tracker X javascript into the browser

new gtm:

gtm javascript loads, pulls down config, streams events to google servers to fan out to tracker X as configured

So blocking gtm.js off tagmanager.google.com / www.googletagmanager.com / the various other domains still blocks all gtm injected tags.

The tl;dr is they're become much closer to segment -- which does the data fanout internally to segment. But they should still be straightforward to block.

This is not how GTM server side works. There is not a single call to Google domains from the client, when GTM server side is set up to its fullest. The config (gtm.js) will be loaded from my subdomain and not googletagmanager.com. Also gtm.js can be renamed.

Per the docs here [1], that is not true. You continue to load gtag.js off the googletagmanager.com domain; subsequent events can flow to a custom domain.

[1] https://developers.google.com/tag-platform/tag-manager/serve...

Couldn't you still recognize the script by its content?

No because the script contents can change from site to site. Maintaining an index for every site would get you closer, but individual sites can trivially tweak things to break fingerprinting as often as they want. Even on every request.

Exactly, this is already done for tracking scripts, since it's commong to use proxies to load tracking scripts.

Not with dynamic obfuscation.