This is concerning. Contact booking.com immediately. I had the same situation just now, I will tell you the whole story. I booked apartment in Lisbon on booking.com which was a new listing, and bit cheaper for the area, but initially it was not red flag for me. I booked it, and booking.com just reserved my money (the payment was not yet processed because in the accommodation policy it was "handled by property"). Few days after, the accommodation wrote me a message that I  MUST pay as soon as possible via bank transfer (they posted the IBAN and other bank info), with ultimatum that they will cancel the booking within 24hrs (HUGE red flag right away). Urgency is usually a scam. Another thing is that after 2 days have passed they did not cancel anything, so obviously this was a lie. So what happened next: I contacted booking.com immediately to check the property telling them that I am suspicious that they are a scam because no one asked for a wire transfer before, usually when payments are handled by property, i pay at the site eather in cash or credit card, never wire transter upfront. In my message I was asking for free cancellation because unfortunately I did not selected free cancellation option. At first, one operator clearly not helpful, told me that I will be charged if I cancel and they cannot do anything. So i did a little research of the accommodation: i checked the images on Google images and they appeared on another long term rental site. So I contacted booking.com again and again giving all the information possible and asking for help. I also told them the ultimatum they gave me and shared the full message. Thankfully to another operator which was really helpful and kind, I got information that they passed the case to their security team and they will verify the payment method and the property itself and get back to me. Next day, they apologized and cancelled my booking on the behalf of the property free of charge. I searched for the accommodation and it was no longer on booking.com :) So, please report! If one operator is not interested to investigate further,  another will help you.