Sorry I don’t see a Mobile-specific forum. This report is for latest non-Beta Brave Mobile (1.5.7 (18.05.01.09)) on New iPad (gen 3 / iOS 9.3.5).
In horizontal or vertical orientation, shields up or down, all are the same.
When scrolling your feed, when you scroll past the point at which the items on the right column leave the screen, that column redraws itself as a top layer over the left side of the feed column and stays in place. Continued scrolling of the feed scrolls underneath this layer, and since it’s so large it makes the site unusable.