Thanks to Kevin Powell, today I learned that the text-underline-offset property is named so because it only applies to underlines and not other text-decoration-line values like overline and line-through.
<a href="https://example.com">Example</a>a {
text-decoration-line: underline overline; /* We can set multiple line-decoration properties at once */
text-underline-offset: 16px; /* Only impacts underline */
}