First, look at the report rather than the conclusion. An appraiser working to Appraisal Institute of Canada standards will list the comparable sales and the adjustments made, and errors are common enough to be worth checking: a missed basement development, the wrong lot size, a comparable from a weaker pocket of the city, or a sale that closed months earlier in different conditions. Documented evidence sent through the lender can support a review.
Second, decide how much speed is worth. If the timeline is fixed by a possession date on your next home, meeting the buyer partway can be cheaper than relisting and waiting. With 1.63 months of supply reported by the Saskatchewan REALTORS Association, a well presented Saskatoon home usually has other buyers, but a second round costs weeks and every buyer's lender orders its own appraisal.
The best protection is upstream. An appraiser starts from the same public record everyone else does, so improvements without a permit are invisible unless someone puts them on the table. Joel Dyck assembles the receipts, permits and photographs before the appraiser attends, so the value being reported reflects the house that exists.