I just observed this random series of dots on the Meta SE front page:
When I zoom in a lot, it looks like an arrangement of epsilon characters. I'm pretty sure it's a problem with the user's name because if you observe the text "answered x minutes ago by...", it's missing the username:
It remains on top of the sandbox post: now that there are new items on the front page, it has moved downwards.
I've tested this while signed in on Brave 0.24.0 for Windows 10 and signed out on Google Chrome 69.0.3497.100 for Windows 10. It doesn't disappear after reloading the page and it doesn't show up on other sites.