Inflation, especially cost of necessities (groceries, etc.)
Buying property is well out of reach for many people
Renting property is increasingly out of reach for many people
Stagnant or declining job markets
Interest rates and the cost of debt
(To a lesser extent) Carbon taxes and cost of energy
And so on. Those problems are related in many ways, and well-summarized by the umbrella term "cost of living," but I think it's a mistake to think of it as a single issue... Both in general, and in the context of "single-issue elections."
That list shows why the carbon taxes will be the target. Those first 5 account for basically all of the increased cost of living, but they are HARD problems. Not one of those presents a simple policy change that could even make a meaningful dent, and no one agrees on even the general approach governments could take to chip away at those.
However, for the last one, politicians can promise to scrap it or carve it up like a thanksgiving turkey and, despite that having almost no effect on the overall cost of living for the average Canadian, it seems like an easy solution.
It's going to be lying about addressing the cost of living. Every politician will promise what ever it takes to get his ass into the chair, then they will figure out how many of their promises are achievable and which ones go against their business interests.