Help With Google Popup Needed

Hi all, my first post and I’m a total airhead when it comes to IT. I’ve used Brave for a couple of years and all good, but today I visited the Reddit site and a Google popup asked me if I wanted to login to Reddit with my Google ID; it had my username and a tab to click.
How is it possible for Google to track my browsing and how are they able to be sharing my personal data?
I use Brave because I thought this browser offered privacy from snooping. Apologies for my naivety, but could someone let me know how this is happening?
tks!

This is because Reddit offers you the option to sign in with your Google account now (you can see this by looking at the Reddit login page). If you are currently signed into your google account (at least this session) that’s likely the reason Reddit is showing you the pop up.

Hi Mattches, tks for the reply. The popup displays my Google username. How would Reddit know this unless Brave browser was sharing this info?

@bumwart,
It is because you have signed into Google and subsequently set a cookie for your session. However, try opening a Private browsing window and then going to Reddit.com – you’ll notice no Google login pop up appears at all (let alone with your login).