This is
Hyatt's official policy.
New reservations booked July 1, 2020 or beyond
With some very limited exceptions, reservations booked on July 1, 2020 or beyond – for arrival dates through July 31, 2021 – can be cancelled at no charge up to 24 hours before your scheduled arrival.
Reservations made after April 1, 2020 at select Destination properties or under Special Event Rates, after June 3, 2020 at Hyatt Residence Club properties, and any other reservations made after June 30, 2020 that disclose a different cancellation or refund policy at the time of booking are excluded from this policy and subject to the cancellation or refund policy disclosed at the time of booking. Please visit the Change and Cancellation Fee Waiver Exceptions for a list of excluded Destination and Hyatt Residence Club properties.
Hotels may adjust this cancellation policy during some high-demand periods (e.g., holidays or special events). When making reservations, guests are always encouraged to review the rate rules, which show the current cancellation and deposit policies for all properties and rates, to ensure they understand the cancellation and/or deposit rules for each reservation.
Reservations can be changed or cancelled on hyatt.com or via the World of Hyatt app (subject to the exceptions noted here and during the booking process). Please note that changes to existing reservations will be subject to availability and any rate differences.
I was going to book Advanced Purchase Rate, with the expectation that I could cancel up to 24hrs prior.
I even called central reservation, who verified this policy and told me that my property of interest was not one of the exception properties.
But I called the actual property just to double-check. To my surprise, they informed me that they have designated literally 40-50% of all the dates from mid-Dec through end-Feb as "high-demand periods" and therefore they will not honor Hyatt's Covid cancellation policy on those dates.
This makes this cancellation policy very disingenous imo. The second to the last paragraph in the quoted info above is an exceptionally important escape clause for Hyatt that I suspect most people will miss. Even central reservation was not aware.
Bottom-line: Before you book that Advanced Purchase booking via Hyatt app, make sure you contact the hotel.