Under certain font sizes, such as 16, it will show like that
but in the font size 23, it shows normally
Obsidian version: v1.1.9
Installer version: v0.15.9
Operating system: Windows 10 Pro 10.0.22623
Login status: not logged in
Insider build toggle: off
Live preview: on
Legacy editor: off
Base theme: light
Community theme: Things v2.1.5
Snippets enabled: 0
Restricted mode: on
First, for the bug report, can you please test with default theme?
I get this same problem with single-pixel lines in other apps. For stuff like this, it might be useful to investigate your monitor/display settings too. There may be sub-pixel, anti-aliasing settings that can help.
This is not a definitive answer. Just a guess. But I think depending on your resolution and anti-aliasing settings, and font, this might be unavoidable and outside the control of any app. I’m not sure this is an Obsidian issue.
(Although since you can take a screenshot of it, I’m not sure exactly what that means. I guess that means it isn’t your monitor. But it could still be anti-aliasing settings.)
I can’t reproduce this in MacOS on a Retina screen. And I tried to find the font smoothing options, and they no longer seem exposed in the settings. So I suspect MacOS is dealing with this issue with sub-pixel anti-aliasing.