Is the magnetometer built into the display in iPhone 12 Mini?

I had Apple store replace my battery today and the rep told me their hardware diagnostic test reported that my "compass is failing." I had noticed that my compass app didn't work, but I always assumed it was a software issue. The Apple rep said it's a hardware problem, and that I need to replace the display for $229. That kind of makes sense because my iPhone has a non-Apple display, and I can imagine that the magnetometer in it failed. But I declined the repair today because I wanted to double-check before spending $229. Is the magnetometer really built into the display in the iPhone 12 mini?

Thanks.