UIGraphicsImageRenderer performs image conversion even if set up using default settings

I am creating an image using the following code:

UIGraphicsImageRendererFormat *format = [UIGraphicsImageRendererFormat preferredFormat];
fomat.opaque = false;

NSError *error = nil;
UIImage *image = nil;
[[[UIGraphicsImageRenderer alloc] initWithSize:size format:format] runDrawingActions:^(UIGraphicsImageRendererContext *rendererContext) {
    //...issue drawing commands into UIGraphicsGetCurrentContext()
} completionActions:^(UIGraphicsImageRendererContext *rendererContext) {
    image = rendererContext.currentImage;
} error:&error];

When executing the line:

image = rendererContext.currentImage;

I'm seeing a call stack leading to vImageConvert_AnyToAny:

If I understand correctly, an image format conversion is occurring, which is unexpected as I am trying to draw in the device's native format.

Are there any workarounds? Or maybe it is the expected behavior and the conversion does not impact performance in any way?