What you're describing is quite normal in cold weather, especially if it was your first time using the departure timer. When preconditioning is on, the car uses battery power to heat the cabin and preheat the battery.
Tutuapp
The Mach-E's 2025 heat pump is a real asset for winter: it provides good thermal comfort without draining the battery like a conventional heater. In everyday use, this means you can get through mild winters without sacrificing battery life. However, it's not a perfect solution for extreme cold...