It’s different because of how the pins are connected. C-to-A uses 4 or 5 pins (with or without id pin) out of 24 in total for USB C. My guess is that it negotiates differently in that scenario. I’m guessing those problematic USB C devices only connect those 4 or 5 pins and don’t properly “talk USB C”.
Framework laptops solve this by having physical switches for the camera and microphone at the top of edge of the screen. Can’t get safer than that except for physical removal.