I believe that someone else is using my phone number to connect to their account. But I’m not sure if they’re trying to get into my account and get my information, or if it’s a mix up

More than likely they mis-entered their own number (transposed digits) in their own account and it happened to be your number so you are getting the text messages.  Hopefully when they don't get the text they will figure it out and edit the number.

For account specific questions or concerns, please contact our Phone Support.

See TurboTax FAQ - What is the TurboTax phone number?

https://ttlc.intuit.com/replies/3300041