Justin Pot, writing for How-To Geek:

Planning on selling or giving away your MacBook Pro with a Touch Bar? Even if you wipe your Mac and reinstall macOS from scratch, it won’t remove everything: information about your fingerprints and other security features are stored separately, and may remain after your wipe your hard drive.

Woah. I was not aware of this. Something to keep in mind if you’re planning to sell or transfer a recent Mac. Hit the link to see how to clear this data.