I can repro, same version of Chrome, Windows 10.
For me it only happens to me when Chrome is in full screen mode
And also
- only happens in Chrome
- the issue disappears when dev tools are opened.
- it only happens when I scroll using my mouse, it does not happen when I scroll using cursor down key
- I can only reproduce on your forum, not in another forum with the same font
- it happens on your forum in safe mode as well
I would reckon it’s a browser bug.
EDIT
Found a similar bug report here 1363981 - chromium - An open-source project to help move the web forward. - Monorail
Repro https://codepen.io/AleksandrHovhannisyan/pen/oNdZxjJ