It's mainly because, apart from the initiatives mentioned, the budget did not include many other commitments, for a variety of reasons determined by the government.
For example, many of the commitments in the electoral platform of the Liberal Party, which forms the government, are not included in the budget. Nor did the budget factor in the pressures exerted by the provincial governments, which wanted more health funding. The budget did not include the commitments made to address these requests, or the government's commitments with respect to increased spending in certain sectors, including national defence, to meet or at least get close to the 2% GDP target.
That's why I suspect the deficit might be higher in years to come, unless taxation is increased to enable the government to meet these budget targets mentioned in the 2022 budget.