Yes, You can add paypal icon the social media bar, to do so go to Themes Directory Folder -> Partials-> Social-bar.php line no.31 and insert the following code with the link that you want to redirect after click.
I could be wrong, but I think that this change got added (accidentally?) to the Circumference code base in the latest (110) release. Nice for me, but I’m not sure that everyone wants a paypal icon (that doesn’t do anything) on their social bar. Perhaps you could add it to the social bar customization options so that it can be configured?
No, sorry, I guess I was not clear. I did NOT update my version of the theme yet. However, when I upgraded to 110 the paypal icon is included. It seems to have been included accidentally in the code base. You will notice that it even appears in the Circumference Demo: