Manufacturers are allowed to add supplementary charging standards on top of USB-C PD

Controversial opinion: I wish this wasn't the case. So many different proprietary protocols, most of the time you'll still need a specific adapter, and in some cases even a proprietary cable to utilize the full speed, and nowadays most devices come without the adapter.
And there's even PPS in the PD spec allowing to request for a specific voltage rather than something in an existing list.

But I do also have some personal grievances here:

1. Mi TurboCharge - This may be something based on PD, but still being something separate. I don't know, but I do know it requires more pins than USB-A has. 5 pins. Somewhere I read this is connected to a CC pin in the USB-C connector. But no, they did not use USB-C, they used USB-A, with an extra pin. Only shortly before the phone died I finally figured out why it wasn't charging as fast as expected - I wasn't using their proprietary cable.

2. My current phone's interference (?) with Qualcomm QC 2.0 - Somehow when using a cable with non-perfect connection on QC-compatible adapters, when I move the USB-A connector, it starts triggering 12V mode until it finally shows overvoltage error and slows down to 7W. QC 2.0 is how my USB tester identifies it. This is a MediaTek-based device, so I don't think it would support QC. The original adapter uses PD and some 11V 6A thing with unknown protocol. Perhaps that is where the problem originates, I don't know what data it sends down. But testing with OTG adapter on the original brick it seems the protocol needs the extra pins of USB-C to work properly.

I've had 3 phones that supported some fast charging, so far 2 of them made it into a confusing mess. Had they all used just PD it would have been a better experience.