Total conjecture but it could be that they need to use up older parts that are going to be updated for the new model year, like the interior front door panels. MIC MYs seem to have the updated door panels with the trim that matches the dash, like the 2021 M3s. Another guess is that they will flip the switch when MY production moves from Fremont to Austin. Who knows. Personally, I don't care about the model year but I would like to have the new front door panels so that my MYLR matches my 2021 M3LR.