Why there is so many clients reaching out but do not confirm the booking?

To respond to your first question, no they are not "fake clients." Rover encourages customers to contact several potential sitters before making a decision. In your case, these customers likely chose to go with somebody else. However, I should caution you not to accept dogs sight unseen. That can lead to many problems with not only the dog but its owner frequently. A best practice to set up a Meet & Greet prior to accepting any potential booking with a new client.

As for your second question about this daycare job, under no circumstances should you accept the dog without getting the official confirmation from Rover about the booking. There is no upside to this type of situation. You might not get paid, and then you have no recourse. So if this person shows up at your door at 7.30am and thrusts the dog's leash in your hand, DO NOT just go along with a promise to take care of the paperwork later. It has to be done prior to you taking custody of their dog.