[tankenmate]

indeed, you need some form of CSRF, but the Sec-Fetch-Site is primarily focused on keeping a browser secure, not the server. Having said that it's nice defence in depth for the server as well but not strictly required as far as the server is concerned.

[nchmy]

I'm confused. In my mind, you only really need to keep the server secure, as that's where the data is. Auth cookies and csrf protections (eg Sec-Fetch-Site) are both used towards protecting the server from invalid requests (not logged in, or not coming from your actual site).

What are you referring to when you talk about keeping the browser secure?

[tankenmate]

The Sec-Fetch-Site header can't be read / written by Javascipt (or WASM, etc), cookies (or some other tokens) on the other hand can be. In most circumstances allowing Javascript to access these tokens allows for "user friendly" interfaces where a user can log in using XMLHttpRequest / API rather than using a form on a page. OOB tokens one a one off auth basis or continuous (i.e. OAuth, TOTP with every request) are more secure, but obviously requires more engineering (and comes with its own "usability" / "failure mode" trade offs).

[nchmy]

> The Sec-Fetch-Site header can't be read / written by Javascipt

Perfect. It's not even meant or needed to be. The server uses it to validate the request came from the expected site.

As i and others have said in various comments, you seem to be lost. Nothing you're saying has any relevance to the topic at hand. And, in fact, is largely wrong.

[tankenmate]

"Nothing you're saying has any relevance to the topic at hand. And, in fact, is largely wrong."; your confidence in your opinion doesn't make you right.

Prove it.