Sorry for the double posting, but this is UX specific to quizzes, so I posted in the quiz forum as well (https://moodle.org/mod/forum/discuss.php?d=415326 ↗).
With Moodle version 4, the course index is placed in a retractable pane on the left and the blocks are placed in a retractable pane on the right, which gives access to the full width of the window, in quizzes, when both panes are closed. It also ensures that the blocks do not scroll with the rest of the page. Version 4 therefore incorporates interesting improvements compared to the current layout. Note that you will still need to click on icons to open the panes and click again on X's to close them.
1) Personally, I would have opted so that we could open and close the panes with a simple hover of the mouse.
2) For example, a button could be added say just above the information button at the bottom right of the screen to adjust the width of the middle part of the page.
3) Also, a class could be developed so that the images and parts of the questions enlarge to the full width of the screen when clicked. Just an idea.
4) I take this opportunity to also suggest that the state of the course index be preserved when you click on an item in this menu. It's a little irritating to always have to scroll from scratch in this menu.
The above four suggestions, 1), 2), 3) and 4), would make the interface more user-friendly.