I have identified that this is a problem with the "Hardware Acceleration" feature when enabled in Chrome settings. It also occurs a smaller flashing black squares in other websites, especially after hours of intense web browsing.

Ending the "GPU Process" from the integrated Task Manager (Shift+Esc) temporarily solves the issue for a few hours then it returns. Disabling the "Hardware Acceleration" feature permanently solves the issue but I guess it might have some disadvantages but I can't seem to notice any degradation in performance with it disabled.

I hope my analysis gives the Chrome developers team some clues to help solve the issue.

Thanks for filing the issue!

Tried checking the issue on reported chrome version 66.0.3359.139 using Windows 10 with the below mentioned steps.
1. Launched chrome
2. Navigated to https://www.zhihu.com/
3. Tried logging in, by changing country.
But we are unable to change the country code, Attaching the screen cast of the same.

@Reporter: Could you please have a look at the screen cast and provide us with sample test credentials which helps us to triage the issue in a better way. Any further inputs from your end may be helpful.

Deleted: 838909.mp4 5.0 MB

	838909.mp4 5.0 MB View Download

The problem you experienced in the video is simply due to your use of Google translate, try to change the country without translating the page and it will work with no problem.

I've also seen this a few times on two separate computers running Windows 7 64 bit stable version of Chrome. I get black rectangles flashing on the web pages. Once, I noticed that the rectangles were over top of some animated content. As stated above, it only seems to happen after a browser has been in use for a while. I just close and restart Chrome to fix it. I also run Chrome Canary on one computer and don't think it occurs there, but I will watch more closely for it there.

jaselford@ - Could you please upgrade chrome to latest stable #70.0.3538.110 and please let us know if the issue still persists or not.

Thanks...!!

As there isn't any info/Feedback from reporter since long time, hence closing this issue and marking it as Won't Fix.

@Reporter: Please feel free to file a new one if the issue still persists.

Thanks!