When playing back still images I like to press the Magnify button to zoom into the image and check for sharpness (especially the eye). When doing this the review image contains a black box (bottom right) with a small square inside it which shows where I am moving the joystick to other parts of the image to try and find the eye. The problem is there is no image thumbnail, just a black box. On my Fujifilm xt4, a thumbnail of the image is displayed so I can see where to move the little square to. This would be a simple and useful refinement to an already excellent camera! Thank you!
Canon has a better way. Canon bodies can zoom in on your locked AF point when you open the photo.