…of a product, and with that, lower demand for it.  This is the sort of thing taught in high school introductory economics courses.  One way to raise the price is to raise taxes related to it, and to reduce tax deductions related to it.

The Manhattan real estate market [a generally hgh-end market] stumbled in the third quarter of 2019, new reports show, as prices plunged and fewer buyers were willing to purchase higher-priced properties in the wake of two recent tax increases.
The median sales price for properties fell 17% from the same quarter last year…. The average sales price dropped 12%….
Condo sales fell 8%….

Maybe this had something to do with it:

In July, New York City increased its mansion tax—a progressive tax that applies to home sales of more than $1 million—to a maximum of 3.9%, up from a flat-rate of 1%. The tax rates vary from 1.25% for $2 million sales, to 3.9% for sales of $25 million and higher. The city also increased a one-time charge on properties worth more than $2 million—known as the transfer tax.

And maybe the $10,000 cap on state and local tax (SALT) imposed by the 2017 tax reform bill is having an impact.