Hey there, sour_puss90!
I see from your post that you've recently gotten a 2013 Mazda 2, and when you connect your iPhone X to play music the repeat function seems to not want to turn off. I'm happy to help.
If you haven't already, I'd recommend checking to see if the stereo of your Mazda has a setting that controls music playback from your iPhone. If turning repeat off directly on the phone does not work, it may be that the car is controlling this function.
Should you still be unable to get the music to stop repeating, try going through If your iPhone, iPad, or iPod doesn't connect to or work in your car - Apple Support. While this article isn't specific to music playback, the steps in general focus on issues with your iPhone and its connection with your car.
After that, my recommendation would be to reach out to Mazda directly to find out if they have any updates to the firmware, or can provide you with direction on music playback control from the car stereo.
If you still need help after speaking with Mazda, please get in touch with Apple Support directly: Contact Apple Support.
Have a wonderful weekend.