SrMi

The noise is mainly determined by the exposure (shutter speed and aperture), not by ISO. That is why some do not see much noise at ISO 3200, and some do. With any camera, to minimize the noise, you want to open the aperture and slow down shutter speed as it fits your creative constraints (DOF, object movement, camera shake).

Do you hear the camera's mechanical noises?
You can switch to the electronic shutter to eliminate the shutter noise.
Closing the aperture to the working value also produces noise. The only way to eliminate that noise is to set the working aperture to the maximum value (f/2.0).

Image Capture transfers image from SD card to your computer. What do you use to view the image (where you see the black bar)?

What kind of raw converter are you using? The black bar on the right side indicates that the software you use does not support X-T4.

Of course, at various apertures.