Why can't my huawei mate 20 pro charge any other smartphones?

I've tried that with the device huawei p20 lite from my brother. Unfortunately, it was not possible. And yes, in the time was also the reverse charging turned on.

Does anyone know why?

Because the p20 lite does not have wireless charging. You might as well try charging a stone with your device.

Besides, that's unnecessary gimmickage anyway. More energy is lost than being charged.