This article lists Manhattan's rent vacancy rate as 10.01% for February-July 2021:
https://www.thecity.nyc/2022/5/17/23108792/nyc-apartment-vacancy-rate-housing-em...
Your source (Corcoran Group) states a 1.7% in May 2022. That's quite a big difference for a one year.
So what gives?
The source in TheCity article is based on a governmental department survey, while the Corcoran number is based on (property rental and leasing) agencies' listings and reports.
The Corcoran report even states (in the smallprint): "Real vacancy is unknown as not all vacant units are publicly listed".
So, what could be a motivation to underreport vacancy and omit unlisted vacant objects, except in the smallprint?
The answer is: "Money".
The article you link to even begins with the words:
"Unfortunately for apartment seekers, record-high rents have done nothing to curb tight vacancy rates market-wide. This limited inventory has kept New York City’s rental market extremely competitive."
The translation is: "It's expensive, but that's totally justified. It's sooo rare."
Could there be a link between rarity, high price and the Corcoran Group? Even the title of their site could have been an indicator: "The Corcoran Group: Luxury International Real Estate"
They are in the business of dealing with expensive apartments. One method to justify it is to communicate rarity.
Another motivation might be that they know the consequences of admitting high vacancy: Eminent domain or vacancy tax, that would pressure them to release the items to the public instead of being able to hoard it to increase prices.
Before you downvote my comment again, please consider why you trust the reports coming from some Luxury Real Estate Company over governmental reports. Especially when the Luxury Real Estate Company admits that the real numbers are "unknown" to them in the smallprint and when their motivation is very, very obvious. (And even stated in the very first two sentences of the article!)
Just why?