I use Magento 2 (Version 2.3.2) with standard luma theme. If i navigate the topmenu down to the 3rd level and hover over some category, that opens up the 4th level, i often cant reach the 4th level categories with the mouse, cause they always open up on top of the 3rd level window. If i try to reach it with my mouse, the whole menu closes. So in many cases i cant navigate to a 4th level category.
Searched all over the internet for this problem. It seems its not even been known so far.