There are different types of AirContact backpacks. Ordered by weight light to heavy: Ultra, Lite, Core, X. The X backpacks also have the highest “max load” recommendation.
So yes, the AirContact Core models are quite heavy, but they are on the heavier side of the lineup. They are kinda the basic model. If you care about weight, maybe take a look at the Lite or even Ultra models.
I don’t have experience with the AirContact models, but I have a couple of other backpacks from Deuter. Good quality, they hold up well. I’m a fan of their “AirStripes” back system which they even use for daypacks.