Model name: CN_AI2203_B
CN version!, I could be wrong because it's really a filthy mess, Asus is ASUS but ASUS Tencent is not ASUS for all services.
So, if I'm right, you are Chinese, you keep CN firmware and you benefit from services and after sales on this sitehttps://rog.asus.com.cn/phones/rog-phone-6d-ultimate-model/
The discussion is herehttps://zentalk.asus.com/zh/categories/rog6d-tw
If you are not Chinese and do not live there it is as if you bought a Samsung product and tried to register it, to have support and warranty on Apple for this Samsung product