Judge David N. Hurd just decided this in A. v. Hochul; it's a temporary restraining order, to maintain the pre-mandate status quo until Sept. 28, when the preliminary injunction hearing will take place. (The mandate requires a vaccination by Sept. 27 for some covered employees and Oct. 7 for others, so its practical effect may be quite short, if the judge hands out a decision on the preliminary injunction at the hearing or shortly after it.) The order doesn't give detailed reasons, but that's not uncommon in such temporary orders.
Because the rationale for the order has to do with the rights of religious objectors (chiefly under the Free Exercise Clause and under federal employment law), the order suspends the vaccine mandate only as to the state's "enforcing any requirement that employers deny [or revoke] religious exemptions from COVID-19 vaccination." It doesn't block the mandate more generally.