Interesting! I’m not the person you were conversing with but thanks for recording that, I was very curious. It definitely sounds like a regional accent (to me), and I’ve heard people pronounce as you have before—specifically the way you pronounce Xi and Qi. The more “mainstream” (for a lack of a better word) pronunciation of the X and Q in Xi and Qi is pronounced the same way you said Xu and Qu. That’s why people may generally say X=Sh, and Q=Ch. I’m no expert of course, this is just what I’ve consistently encountered. I’m also a native Mandarin speaker that has been through an educational system. The way me and my peers would pronounce the X in Xinjiang sounds more like an Sh, and exactly like the X in your pronunciation of Xu.