Regardless of the build number currently all version 12.0.731.x builds of Chromium which I checked (80976, 81012, 81026 and 81028) have the scrollbars broken. Actually the scrollbars do work as intended, but they are not displayed correctly as they flicker and display rubbish. This bug does not appear in the earlier version 12.0.730.x builds that I currently stick to.