New York State has had a challenging set of rules for travel. Anyone arriving from a state with more than 10 positive cases per 100,000 residents on a rolling average basis, or greater than 10% of Covid-19 tests coming back positive has had to quarantine for 14 days on arrival. Enforcement has been spotty.
With very few states left on the list of allowable travelers entering New York, the state is replacing that regime with mandatory pre-travel testing and shorter quarantine on arrival with a second test for everyone as an alternative to a 14 day quarantine.