I solved it.
Don't look at the Samsung partnumber for the camera. Take a look at the physical camera in your phone. On the flex cable that connects the camera to the motherboard there is a modelnumber. Either W12SAR2 or W12LAR2.
If the supplier you are buying the camera from do not list this specific information, ask them.
My original camera was a W12SAR2. I ordered the GH96-13921A (for the S20 FE 4G). The new camera wouldn't work as it was a W12LAR2.
I then bought a GH96-13893A (for the S20 FE 5G). This was a W12SAR2 camera. It worked!