I don't think it's 100% accurate to call the budget "austerity".

The budget projects increases in both revenue and spending, and increases the deficit by ~50% percent.

What the government has asked for is widespread cuts across the board from current programs and operations (and staffing) to try to make more room for new spending in new areas. They are targeting getting to ~$13 billion CAD reduction in annual operations cost by end of decade.

By contrast, there are a lot of major spending programs - ~$10 billion CAD added to the defense budget, ~$5 billion CAD in tariff relief.