A CSS snippet to style internal Obsidian links in edit mode as dashed underline to make it easier to notice which items have notes and which don’t (or which are mistyped).
Store it in [YOUR_VAULT]/.obsidian/snippets/links.css.
.markdown-source-view.mod-cm6 .is-unresolved {
text-decoration-style: dashed;
text-decoration-line: underline;
}