If your card has 3 fans, then all 3 should spin when you set them to 100%.
If only 1 of them is not spinning, even with fan speed set to 100%, then its is indeed broken.
I am sorry to hear that you have this issue. Make sure to contact your vendor for a replacement card.
This is a hardware problem which is covered by your warranty.
Just in case: Are your power connectors connected to the graphics card correctly?
Make sure they are sitting tight and all the way in - maybe even reconnect them and check the pins.
--- [ CPU: Ryzen 7 3800XT | GPU: ASRock RX 5700XT Challenger Pro 8GB | driver: 24.1.1 ]
--- [ MB: MSI B550-A Pro AGESA 1.2.0.7 | RAM: 2x 16GB 3600-CL16 | chipset: 6.01.25.342 ]