My understanding about the food service on this equipment is that due to the high capacity and space limitations, there are not enough ovens to heat the meals for the entire plane. This means that the service has to be done in three phases.

As it is a new aircraft, it will likely take a little while before the staff are familiar with the newer service delivery as not all crew are subject to this equipment on a regular basis.

This does not excuse Air Canada's decision to go high density - a bad customer move in my opinion. People will fly the equipment type once and then never again.