No, it can do more than that. For example it can tell the site whether the user is using a browser that is based on Chromium, which they can then use to deny you access if you don't. Since Manifest V3 has killed adblockers in Chromium-based browsers, this will mean if you need access to a site that does this, you will need to use a Chromium-based browser and see ads.
Looking at the proposal, it will also tell them which OS you use, making it even worse.
No, it can do more than that. For example it can tell the site whether the user is using a browser that is based on Chromium, which they can then use to deny you access if you don't. Since Manifest V3 has killed adblockers in Chromium-based browsers, this will mean if you need access to a site that does this, you will need to use a Chromium-based browser and see ads. Looking at the proposal, it will also tell them which OS you use, making it even worse.