When I expand the Indesign window to fill 90% of my 27" screen, I get numerous black horizontal lines appearing when scrolling. Other editing functions typical when handling type on a layout also produce random broken lines. If I click a page forward or back arrow, the lines disappear. I was first using v16.2 and just upgraded to 16.3.2 today with same results. Just discovered I have to reduce the widow size to about 75% of my screen size for the lines to not appear at all. Never had this happen on previous versions and need almost full screen width to handle complicated layouts. IOS Big Sur 11.4 on 27" iMac.