Current workaround
Markdown links do not show preview on Ctrl+hover in edit mode yet, so I have to switch to “preview” mode, locate the link, see link color, switch back and locate the link again.
When using wiki-links, I have to grab mouse, press Ctrl and hover over the link.
Related feature requests
keywords: differentiate, display, distinguish, missing, nonexistent note/file, non-existent, style, target, visually distinct