Based on this the bug has been fixed in version 2020.2. I have version 2020.3. But I still the same nsbp shows as regular space with some background highlighting in markdown files.
The fix for this issue was making Editor honor the registry setting: Help | Find Action | Registry | editor.show.special.chars. You can disable this option to get rid of this representation.
Maybe someone else will help this. Now special characters are not visible:
However, in this case, it would not be bad if the characters were displayed as in html and php files:
Hm, I can't reproduce it on PhpStorm 2020.3 both in Editor and Preview Markdown panes, no special symbol is shown:
Is it reproducible for you in other files as well?
The support team answered:
The fix for this issue was making Editor honor the registry setting: Help | Find Action | Registry | editor.show.special.chars.
You can disable this option to get rid of this representation.
Maybe someone else will help this. Now special characters are not visible:
However, in this case, it would not be bad if the characters were displayed as in html and php files:
Great, thanks for the update!