It's not that strange. USB-C is a plug, not everyone who implements the plug also implements it correctly. Some chargers with a USB-C Plug might just send a fixed voltage over the cable, rather then implementing the protocols.
I'm not saying that's the case for you, but USB-C is a minefield and I've seen some weird things happen with USB-C plugs.
I'm not saying that's the case for you, but USB-C is a minefield and I've seen some weird things happen with USB-C plugs.