Here's the deal as linked Crain's NY article spells out:
https://www.crainsnewyork.com/politi...-spending-plan
(If you cannot open link look up story on internet, it's not behind paywall for me).
See also:
https://www.bankrate.com/taxes/sales-tax-deduction/
NY like many northeast states along with CA and a few other liberal democrat socialist bent places have long taxed the *F* out of inhabitants and businesses. They do this because running a welfare state requires huge infusions of cash taken from those that have to be given to those that don't.
That being said each increase in taxes, fees, surcharges or whatever is done with a wink and nod. States raise rates knowing those exposed to some extent could deduct things on federal taxes which provided some sort of rebate. SALT deduction cap has unclothed that nakedness in that those who are being soaked for local taxes now have their eyes opened.
Economists on both sides of fence have been calling for ending or restricting at least two federal tax deductions; home mortgage interest and state/local income taxes. Both are seen as (rightly) benefiting higher income households, and cause distortions in federal tax code.
Problem is going back to early 1900's when federal income tax came into being (and thirty years later for sales taxes), both have existed for decades and were in large part needed to overcome (mainly GOP) objections to creating a federal income tax scheme at all.
Over years as standard deduction has increased fewer households have itemized on their federal taxes. After 2017 tax "reform" even fewer could, hence all the noise about SALT deduction caps.
New York democrats are in a tight spot; under King Cuomo they've taxed, levied fees, and surcharged nearly everything but breathing in this state, and as result people were already leaving. Then came SALT deduction caps *and* pandemic piling on...
Democrats picked up several House seats in last election in large part based upon promises they would repeal SALT tax deductions, good luck with that.