I have been on Airbnb for over 10 years, using it all over the world and never left a bad review, not once. But this is the exception, because it was arguably the worst experience we've ever had travelling, and also put our health and safety at risk.
There were the 'small things', like no key when we arrived (with incorrect instructions), stained bed sheets when we eventually got in (with them arguing with us that 'the cleaners confirmed it was not stained'). And then also forcing my pregnant wife to drive a few miles to go fetch a spare key (even though they messed it up) to a place with no Covid precautions and forcing her to go into some cafe to get keys from some random person, and wouldn't bother to even bring the key. But if we thought that could not be topped, it did.
The house was filthy. It has bed bugs, and we were bitten so bad that we have huge swelling all over our bodies and faces, turning yellow. It's not small, it's really really bad. And so we had to pack up and leave because it was a health concern, and it was by then also obvious that the apartment wasn't cleaned properly and so Covid risk (despite trying to charge us huge sums to have it 'professionally cleaned' which was obviously not being done). We also had to spend extra money on medical supplies, driving back early and now having to redo the trip etc, so not only did they charge us for a weekend we didn't have (and service they didn't actually provide), but actually increased our costs.
The cherry on top is obviously throughout all of this, the constant fights from their customer service, having to always 'prove' things from our end (photos), not bothering to even help us find an alternative when we were in need (they knew what an important trip this was for us), and of course saying they will only refund 25% despite creating all this hell and us now even using the place that is full of bed bugs. We are trying to report them to the police and home owners and neighbourhood and government bodies but they are also not giving as the contact details as required by law. So now we're doing it ourselves.
Again, never complained about any Airbnb, sometimes it's not perfect and that's okay, but this is a borderline criminal enterprise.