I regularly get calls on my iphone now that say (maybe: Jane Doe) under the name, and they are usually correct. Often they are recruiters, or lawyers, or people that I imagine have their phone number publicized on the web. But I'm not sure I've read where apple is getting this info (or perhaps it is a carrier thing?)
It gets the information from other (Apple-only?) apps. From Apple Support[1]:
> iPhone automatically suggests new contacts from messages you receive in Mail and invitations in Calendar, and from other apps. To turn this feature off, go to Settings > Contacts > Siri & Search, then turn off Find Contacts in Other Apps.