@Sandra544 This is not the case. What @Mike-And-Jane0 is doing once again is "putting the cart before the horse". Airbnb cannot legislate on UK Law as it is beyond their jurisdiction.
It does depend on the date of the contract in force, but since 14th March 2020 there has been specific terms in the Airbnb Guest/Host contract which excludes any full refund Covid-19 related cancellations as Covid-19 was then a known risk and guests who booked did so fully aware of the risk. In managing this risk, guests should have put in place appropriate travel insurance to cover any potential losses. (including the change of law).
The post March 14th EC policy clearly states..
... COVID-19-related circumstances not covered include: transport disruptions and cancellations; travel advisories and restrictions; health advisories and quarantines; changes to applicable law; and other government mandates such as evacuation orders, border closures, prohibitions on short-term rentals, and lockdown requirements. The host’s cancellation policy will apply as usual.
It is clear, that in any case of a cancellation, that the host's cancellation policy will apply as usual.
Initially, before ever the frustrated contract condition be taken into account there needs to have been a cancellation. Airbnb are NOT UK Government Lawyers and Judges rolled into one. Airbnb are in no position to sit in judgement of any 'possible' frustration and find in Guests' or Hosts' favour. All Airbnb can do is administer the letter of the contracts in place which they instigated. These cannot be changed. Only UK Law can judge whether this is legal or not and every case will be individual and after the fact.
We, for instance, let our Airbnb as a single accommodation without charge per guest but as a whole accommodation. Limiting the size of the group in attendance is entirely down to the guest. If it is illegal to attend with more than 6 guests then there needs to be only 6 guests in attendance. Guests are quite capable of reducing the size of their group in attendance to be complicit with the law, and as frustrating as this is we've already had many groups need to, and have done this. One group of eight, who lived together, didn't need to. I've heard that other groups who were attending 'an arranged sporting event' didn't need to either. So not all groups greater than 6 are affected.
Like speeding, it would be great to travel at 90 Mph everywhere - and the car is capable - but legally you're not allowed to do that, and you need to adhere to the law. Not attaining 90Mph everywhere is not the fault of the car.
The Airbnb Guest /Host contract says that - Changes to the law are not covered, and the Host's cancellation policy will apply as usual. The logical deduction is that guests will not get a full refund, they will get the refund which is assigned to their contract by the hosts cancellation policy.
If guests are not happy with that arrangement, then they should take up their complaint at court in the UK Legal system.
The CMA, or Competition and Markets Authority have their own view on this.. This is not law. (Although many like to claim it is...) They are advisory's, and it is their opinion. This is their interpretation of matters and is not law until a specific case is taken and judged appropriately at Law. Their covering introduction states this quite well, they say "This statement should not be regarded as a substitute for, or a definitive interpretation of, the law. Rather, it sets out the CMA's views as to how the law operates, to help consumers understand their rights and to help businesses treat their customers fairly. Ultimately only a court can decide how the law applies in each circumstance."
Guests are in no position to claim "frustrated" contracts with Airbnb as Airbnb are in no position to judge on this. Airbnb can only judge on their own Airbnb Guest/Host contract. Getting this wrong for them, will lead to many more arbitration or potentially (now) group action claims against Airbnb for failing to apply their Guest/Host contract correctly, specifically in this case as defined in their March 14th update.