The blog post elaborates. But to summarize:

1) The annoying Sign in with Google banners appear in Firefox and Safari with no toggle to disable them, even if you aren't logged in with Google, even if you don't have a Google account.

2) Those banners do not appear at all in Chrome.

3) There is a Chrome-specific sign-in UI, but it appears only if you're already signed in to your Google account in Chrome.

4) You can disable the Chrome-specific sign-in UI in Chrome settings.

So Chrome users have control, whereas Firefox and Safari users are inundated with annoyance.