Well I'm not sure there is a bug per se. The V4L2 and INDI Webcam driver are treating the camera as if it is a webcam. You can't set arbitrary exposures on a webcam. However, you can set frame rates and sometimes that will change the exposure time. When I wrote the INDI Webcam driver a couple of summers ago, I added a feature to it where you could set an exposure time and it won't change the cameras actual exposure time since for many webcams that is impossible, but it will stack multiple frames together either averaging or integrating them to get a better image over the longer time.