I could verify this on Windows and Android.
Obsidian version: v1.1.16
Installer version: v1.1.9
Operating system: Windows 10 Home 10.0.19045
Login status: not logged in
Insider build toggle: off
Live preview: on
Legacy editor: off
Base theme: dark
Community theme: none
Snippets enabled: 0
Restricted mode: on
If the official answer to this bahaviour is “Works as expected”, I recommend changing this expectation because this behaviour creates problems for users.
And ---<space> is used in YAML for directive indicators, such as between log items.
In both cases they seem to pass POLA (for users who are used to the specs). Both are outside of Obsidian’s control, I think, but perhaps could be raised with the people responsible for YAML and Markdown specs.
As such I think that invisible trailing white space is not a great idea in any interface. Hope that Obsidian will one day add a core option to display white spaces and non-printing artefacts in edit mode.
EDIT: At least users can see by the onscreen formatting in edit mode that the text is being rendered as YAML (guess that might depend on the theme used) and so know that something needs changing, and when viewing in read mode Obsidian will give an ‘invalid YAML’ warning. Safety nets, of sorts? Writing aids?