Android Chrome, too. If I am in the middle of the page and want to repeatedly alternate between scrolling up and scrolling down, I can't simply swipe up, down, up, down. Instead I must swipe up, up, down, down, up, up, down, down. The first of each swipe pair seems to move stuff just a pixel or two, i.e. some container of everything, not just the body element as expected, has a sliver of overflow with scrolling enabled.