https://cs.chromium.org/chromium/src/device/bluetooth/bluetooth_remote_gatt_descriptor_mac.mm?sq=package:chromium&dr&l=186

  return out << "<BluetoothRemoteGattServiceMac "
             << descriptor.GetUUID().canonical_value() << "/" << &descriptor

It says BluetoothRemoteGattServiceMac and then prints the descriptor's uuid. It should probably start with BluetoothRemoteGattDescriptor print it's uuid, then characteristics, prints it's uuid and finally BluetoothRemoteGattService and print it's uuid.