If you use Siri on an Apple computer, and share an iCloud account with someone, including contacts, it’s possible that Siri will incorrectly identify who you are based on what is set for “My Card” in contacts.
To clarify, we’re talking about having an additional shared iCloud account in System Preferences > Internet Accounts. Not, System Preferences > iCloud.
So, let’s say you share a list of contacts through iCloud with someone in this way. Even if you subsequently disable the shared contacts, Siri may still remember your name based on that original “My Card” information.
To repair this, make sure the Contacts are activated under Internet Accounts. Then select another contact as “My Card” in the shared Contacts. Test Siri by saying “Hey Siri, What’s my name?” Siri should tell you the name you selected as the My Card contact. Then change the My Card to a contact in your own personal iCloud contacts. This should fix the problem.