Privacy issues

So my theme recommended this plugin and I installed it today and chose an Avatar for every author we have. I was suprised when for one user WP User Avatar already had chosen a picture that was not even in our media library. So: How does that work?

My guess: This user works on other blogs, and they probably use this plugin there. So when WP User Avatar checked his e-mail-address they found this other blog and the related pic? So WP User Avatar stores e-mail-adresses and data on which sites with the plugin the e-mail-adresses are used?

What happens with that data? I think we should know.

https://wordpress.org/plugins/wp-user-avatar/