Am I missing something? It was the advertised range for P3D+. You can even check the old web page (wayback machine)
You then said it yourself, 310 mi in the last paragraph.
That was the 2018 and 2019 models. For the 2020 model (yours was December 2019 so it definitely was a 2020), the advertised range was 299/304/322.
2018/2019 had 76kWh at 310 rated miles before degradation showed.
2020 had 77.6kWh at 299rmi(20") before degradation showed. (Or 304rmi or 322rmi, depending on which wheels you select, it doesn't make any difference though, that's all the same amount of energy & range assuming you have the same wheels on.)
Now, if they did something different in Canada, maybe there's an error here, but the fact that changing the wheel selection changes your range means that I think it's the same as the US. Easy to tell from an appropriate picture of the energy screen in any case.
Think about the energy you have remaining, not the miles, it is less confusing (though equivalent).