Their "Book with Confidence" guarantee (!!!) is here
https://www.vrbo.com/lp/b/bwc-guarantee
Notably, it says "Seek a refund from the host prior to seeking a refund from Vrbo."
In other words, they can't be arsed.
They do, however, list this as a scenario covered by their guarantee:
c. Material Defects at Properties on Vrbo Sites: Vrbo is not a party to the rental agreement and Vrbo does not own or operate the homes listed on its site. Nevertheless, Vrbo will assist when an undisclosed material defect makes a property inherently unusable or violates a Vrbo policy in manner that cannot be promptly remedied. It would be impossible for these Terms to list all scenarios where this may be the case. Rather than limit this provision to only provide coverage in a small number of listed scenarios, Vrbo will use commercially reasonable and fair judgment to determine whether a defect is material or not. By way of example only, the following misrepresentations are material defects:
i. The stated number of bedrooms or bathrooms is incorrect
ii. The physical location of the property varies significantly from the listing
iii. A health and safety hazard prevents staying at the property
Objections related to cleanliness and minor amenities that are not operating properly are not considered material defects and will not be covered by these Terms unless they create a health and safety hazard or violate a Vrbo policy. Pools and hot tubs with significant and lasting issues preventing use are eligible. All reports of a material defect at the property must be made to Vrbo promptly after arrival at the property or appearance of the defect. If the listing details disclosed the defect and a guest rented the property despite this, the defect will not be covered under these Terms.
The moral of this story is that Vrbo is a terrible way to book a holiday. I'm never going to consider them a reputable bookings operator and will make every effort to advise others about this.
Like PPs I am suspicious of the rave reviews on their site (not just for this property) and suspect they are skewed somewhat by the close interactions they force with the property owners, including mutual feedback. I had a pretty awful stay in one of their properties but was too scared to review it honestly in case the owner gave me a low score that would negatively impact any future bookings.
In short, Vrbo are just in it for the money.