Comment by fweimer
Add the end of https://www.paypal.com/us/home there is a Hewsroom link to https://newsroom.paypal-corp.com/ . They use https://about.pypl.com/about-us/default.aspx as well. At one point, employee email accounts used paypal-inc.com. It might not even be a SEO thing, it could just reflect their corporate structure and the different IT teams.
I agree that it is confusing.
It's a little annoying, but as long as the main domain has a paste that links to the dodgy-looking domain then it's bearable.
Ideally, companies would have a page "all the domains we use" as part of their footer links.
So many companies that should know better are helping to enable phishing by using random domains.