Steps to reproduce
enter zero-width non-joiner in editor. or copy and paste next line:
Expected result
What you should see is what is shown in the forum. A bunch of spaces with ZWNJ characters in between which are not visible.
Actual result
what actually happens is this:

Red dots replacing ZWNJ characters.
Environment
- Operating system: windows 10 19041
- Obsidian version: v0.10.9 (though it was present as long as I used obsidian.
Additional information
I also used the inspect element to see what it shows, it seems that CodeMirror puts it into this class block invalidchar. And in the styles section: .cm-invalidchar.
This is a pretty important character in languages where they have a complex writing system, like Persian and Arabic.