Maybe the car charger burned the power circuit board of the Xiaomi phone. Recommendation: Use a car charger with high safety. Recommend brands like PISEN, SONY, canonCanon, NOKIA NOKIA, nikon, Nikon are relatively good with various protection measures done very well.
If the function can automatically recognize the current of the phone, it will recognize the phone itself, and charge the phone with the current that is most suitable for the phone, the possibility of failure is almost zero.