This issue has plagued InDesign for at least 5 years. There are many posts online about it so I'm not the only one. Whenever I open an InDesign file that's older than my current version, black artifacts start to accumulate on the rulers. I can zoom and they disappear. But once I start working at 100%, they reappear and start to accumulate again. It gets to the point that the rulers become illegible.
I'm using the latest macOS, on a 5K iMac. Not that that matters because this issue persisted with previous Macs that had lower screen resolutions. It also happens currently on my MacBook Pro 2015 with retina screen.
I'd love it if Adobe could resolve this issue. I've posted tweets on Twitter about it several times, and have contacted support in the past, but it never gets fixed.
I have not seen this problem reported before nor have I experienced it myself on similar Mac computers. Do you have any third party plug-ins installed with your InDesign (or perhaps even your Mac OS)? If so try disabling the plug-ins and see if the problem persists.
Since posting this topic in 2019, I have replaced the hard drive with a 2tb SSD, as well replaced the 5K display on my iMac. And no matter how many new releases of InDesign come out, the same display issue happens.
If I open a legacy file and save it, the black artifacts start to appear and accumulate on the rulers. If I start a brand new document, this never happens.
Today I opened an ID file from last year, saved it, and made some edits. As I worked, black artifacts began to appear. If I zoom or do anything while using the ID interface they go away, but then they start accumulating again. Really maddening after all these years. My iMac is from late 2015, still fast and still working perfectly, and running Big Sur with the latest macOS update.