Freshmaker

My image is too dark at 1/15 f5.0 800iso in a brightly lit room, I compared it to an image from another user's x-t20 that's 1/35 f5 640iso and it's normal. My image should be even brighter but it's very dim. Only when I open aperture to max 2.8 and ss to 1/20 or lower and at least 800 iso will it look properly exposed. Is something wrong with my x-t20?