Bad estimates with delayed charging?

I use delayed charging at home (level 1) to charge my 2023 EUV overnight. Usually it works just fine, but I've noticed lately that it's wildly off.

For example: get home and plug in at 8pm. The display says that it will start charging at 1:45am to be completed at 7am. When I open the app at 6:45 to do a remote start, it tells me that charging will be done at 8:30.

My first thought was that it probably has to do with the cold (car in a detached, unheated garage, overnight temps around 20F) but I don't remember this happening last year. I know that it takes power to run the battery heater (sorry if that's not the technical term) which reduces the power available for charging, though shouldn't that be part of the calculation the car does? It doesn't seem to make a difference if I'm charging to 80% or full.

Is anyone else having this issue? Is there something causing the car to make bad estimates about charging time? Or is there something weird with my car or home electricity?