Fast charge is universal, they use backward compatibility mode, you can have fast charger, universal slow charger.
30w can also be charged with a 33w charger, but doing so for a long time is not good for the battery, because it is beyond the safety setting value, which will affect the battery life.
The Mi 10 battery capacity of 4730 mA was fully charged in 65 minutes (30 watts of flash charge). Redmi k30pro battery capacity 4700 mah official website opened the press conference 63 minutes full (33 watts flash charge) universal.
The Mi 33w fast charge and 30w fast charge are universal, but the maximum output power of the wireless charge is less than 30 watts. Under normal circumstances, the output power of the corresponding charger is larger than the maximum output power of the wireless charge. When the 33-watt charging head supplies power to the 30 wireless charge, the charging head and the wireless charge themselves will have a certain loss, so they can be used but cannot reach the maximum power.
Xiaomi 33 watts fast charge and 30 watts fast charge, can be universal. The mobile phone manufacturer is one, and then the fast charge scheme is the same. The fast charge protocol he uses is backward compatible, so the 33 watt fast charge can be common with the 30 watt, but the maximum power of the 33 watt fast charge is 33 watts, and the 30 watt is not reached. I hope it was helpful.