The first measure is taking the ratio of CPI-reported "rented accommodation" to median regional household income and normalizing:
The second measure is taking the same income but using CMHC surveyed rents
The discrepancy between the two measures is marked, certainly something I would investigate further if I had the time.
Despite the discrepancy, both graphs indicate that, in terms of median incomes, rents in Greater Vancouver have not drifted significantly over the past 20 years. That does not necessarily mean there is no regional affordability problem for certain income tiers or regions (such as the City of Vancouver proper) but on balance I don't see much evidence to support Vancouver being significantly less affordable in terms of baseline shelter costs compared to the past two decades, though last year's CMHC data indicate affordability measures are near the top end of the band, mostly due to income stagnation but also in part due to increasing real rents.
Something to keep in mind when considering the recommendations of an "affordability task force".