I added just a battery to a MG24 for testing and get 6.3mA while running my code and 44uA in deep Sleep, connecting USB runs -26mA into the battery which is fully charged.
After Serial.begin() it is as follows 17.8mA running and 1.2 - 2.2mA deepSleep.
After a power cycle it is 17.2mA and 166uA and the USB unplugged.
Interestingly it is 17.2mA and 924uA while the USB cable is plugged in but not connected to the computer side. Unlugging the cable still have it at 911uA, seems a power cycle is needed to drop down to 166… weird.