I (36M) just found out my partner (35F) of 6 years has been lying about her career. How do I bring it up?

I have been with my partner for 6 years and for that whole time she has told me that she is a Registered Nurse at the local hospital. I never had any reason to question that for the last 6 years. But now I believe she is actually a nanny, not a nurse.

How I found out:

We let someone borrow her car for a roadtrip so we put an airtag in the car for our peace of mind (the borrower knew). When the car came back I forgot to take the airtag out of her car. A couple days later my partner pocket dialed me while I was at work and I could here kids in the background. So I immediately texted her back to make sure everything was ok. Then I remembered the airtag was still in the car. When I checked, her car was not at the hospital, but actually at a Doctor’s house that she babysits for on the occasional weekend.

That night when she got home she had this crazy story that she took the train from the hospital and ran into that Doctor’s family on the train, that’s why I heard the kids. When I asked her if she parked her car at their house she said “No, I left it at the hospital”. I decided that I needed more evidence before I confronted her so I let that lie go.