>> City valuations can often be 10% or less of the true market value

> this is, at minimum, a 10% increase in ALL property taxes

If they're ~10x'ing the erroneously low valuation to true them to market value, then that would be more than a 10% increase.

>> Since valuations will skyrocket, the tax rates will fall to compensate

But as the article points out, this is an expected outcome and will be blunted by subsequent tax rate decreases.

All things equal, undervaluing properties for tax purposes isn't fair, although it may be politically (corruptly) popular.