Preview image and actual image not same

Hello there,

iv been using lightroom cc mobile app on iphone 11 to take photos in pro mode.

iv been noticing that after making my settings depending on lighting conditions like setting iso and shutter speed, while i see a crisp image on the ciew finder and the preview. However, once i navigate to the lightroom folder to open the captured DNG image, its just compeletely under exposed. This is really annoying me and im unable to find a resolution to this. Kindly suggest an apt method to overcome this.