Keep in mind DRIVING it is the best way to warm up the battery. And that is FREE heat (normally waste heat).
If you do not need full power in the first mile or two of your commute, I see no reason to waste grid power on heating the battery beyond the bare minimum to get you rolling in the morning.
In the Ford gas/electric hybrid I own (NiMH) they did away with the grid powered battery heater after the first iteration of the vehicle. It just wasn’t needed since you had gas as alternate power. They programmed the car to do a few (usually three or four) 25% discharge and recharge cycles (1.6 kWh battery) in the first 10 minutes when cold. This warmed the battery nicely.
I suspect the maximum power tapers down as temperature falls. But starting with 160 kw, if output were cut in half, you wouldn’t even notice 99% of the time.
Battery conditioning comes on much more frequently in summer. Especially while charging at high currents on a hot day.