Chosen Solution
When I take and view photos using the rear camera there are green lines which render the photos unusable. The phone does have water damage indicated by the sticker in the sim tray but the device still works fine. The front camera works perfectly though.
Most likely the rear camera needs replacement. You can buy a replacement part from here: iPhone 6s Plus Rear Camera And here is a guide to replace the part: iPhone 6s Plus iSight Camera Replacement On a side note, wow that camera is expensive.
