Glad you noticed so early. I had this happen to one of these a few years ago and wasn't so lucky. It was a clear one and I didn't notice anything was wrong until I'd inflated it (using an electric pump) to 45-50" and tried leaning on it to see how tight it felt and it popped. One of the sides of the "paddle" was barely stretched at all, while the other was clearly stretched.
No idea if it's considered a defect, or if you simply have to pay a bit attention and stretch it or squeeze the air over "to the other side" to make it inflate evenly.
If noise is a concern, I'd recommend using one of those large handpumps meant for air matresses or inflatables. It's a bit of work, but it's better than blowing big balloons up by mouth.
This is what I've been using sometimes:
https://productimages.biltema.com/v1...-330_xxl_1.jpg