This is an email that is legitimately sent out when someone tries to file a return using the SSN of a previous customer. It is most often a false alarm, such as when you make a new account for some reason and file a return, your old account will be notified, because Turbotax doesn't know if the new account is also you or someone else.
It can also be a legitimate warning that someone else made an account with your SSN and tried to file a return. You may be the victim of identity theft.
And lastly, scammers can copy legitimate emails and change them for their own purposes.
I would call customer support and talk to the security team. Here is the support number posted on a legit Turbotax web page so you know it is the correct safe number to call.
https://support.turbotax.intuit.com/contact/
