But they also introduced a new console and probably changed its advertising strategy on steam to promote it, probably taking away space that previously was used for the deck. Also, I think people are less likely to buy something that is perceived as old and because there is a new console, the thing they sold before now feels old. Additionally to all of this, they also introduced a new controller that seems to be doing pretty well, probably also taking advertising space away.

No doubt the high price of the deck has an impact, but I would say that there are multiple reasons and not just one.