LibreWolf

I was reading various old posts and the librewolf faq, but none answer my question, so here I am.

Following scenario:

I have the setting against fingerprinting enabled, which is probably the reason why a new private window opens at a set height and set width, 900 and 1600 respectively per about:config.

Now! If I maximise the window, then the inner limits of the window with a webpage do not change (as far as I can tell), what does change is that the original window is embedded now in a bigger window, the bookmarks bar (which I view as separate from the window where a webpage itself is) does stretch to fit to the new size - but as I understand fingerprinting, it's only about the part where the webpage is, not the bookmarks bar or the textbox for the address.

So why does every resource keep saying that maximising the window makes it easier to identify the user if the relevant part of the browser is kept at set height and width even if the window is being maximised? Why having the webpage kind of embedded in a bigger window if it doesn't serve its purpose: Making sure the window is the same size for every user and thus helps against fingerprinting?

Sorry if it is a duplicate, as I said I read old posts and the librewolf faq to no avail.

Thanks!