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I guess this is only partially true, as I have a A-to-C charger cable from Huawei that works with everything except my Pixel 4A phone. And my Pixel 4A phone works with everything except that specific cable.

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USB A->C cables are supposed to have a Rp pullup on CC1, and leave CC2 disconnected. Huawei made some A->C cables which (incorrectly, and spec-violatingly) have Rp pullups on both CC lines, which is how you signal you're a power sourcing Debug Accessory

Your Pixel 4A is entering debug accessory mode (DebugAccessory.SNK state in the USB-C port state machine); other devices probably don't support debug accessory mode and just shrug.

Maybe the cable is missing the CC pin resistors (all USB-A to C cables are supposed to have them to identify themselves as such), and maybe only the phone cares.

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