Does it only apply if the property you made the reservation with cannot accommodate you in-house? Or does it still apply if the property can still house you, but not with the room type you booked? Keep in mind that booking types are pretty broad across the portfolio. This could mean a difference as simple as getting a 2-Queen when you booked a King, or something far more significant and/or inconvenient such as a family with kids being bumped out of an Exec Suite with a connecting room into an individual multi-bed room + cots, or being denied a private villa for something considerably less. Compensation level is status dependent, but the threshold for entitlement to compensation is something that should be (in theory) consistent or fixed.
I ask because the property I'm currently staying at tried to change my room type on the evening of arrival due to "overbooking" - a whole two days after I checked-in (with the correct room type) on the app. It was switched back very quickly upon initiating a chat session, so things turned out fine. However, another recent thread on the topic of the Ultimate Reservation Guarantee has caused me to consider that the definition of "reservation" and the meaning of "for any reason" and "for some reason" are factors to consider here.
I'd argue that the "reservation" is whatever I booked and confirmed (especially after the online check-in has been executed) only has one definition. An offer of accommodation that does not exactly match (or perhaps exceed) what I reserved would be a failure to honor my reservation in my mind.
What say you all?
Here's the link to the Ultimate Reservation Guarantee: