Canon 5D Mark IV Sensor Issue discovered by Michael Andrew. The defect is visible only when you test your 5D Mark IV on a specific way which is described below
Also take a look at the test process steps described by Michael
1. Use your hand or a piece of cardboard to over-expose in the left 1/3 part of the frame shooting RAW
2. Bring the file into Camera RAW
3. Bump up the exposure +1 or more (this makes it easier to see)
4. Raise shadows. It will look like the images below if you have it:
Better you should look at the video and get the more details
Share your thoughts and suggestion with us, also let us know if you find any issue with your 5D Mk IV.
more info available at Michael Website