Within the new PostCSS for the off-canvas dialog, we neglected to include an ampersand (&) within a nested PostCSS block (see https://git.drupalcode.org/project/drupal/-/blob/10.0.x/core/misc/dialog...).
There are no differences in the visual styles because the values fall back from the correct CSS custom property to the the same value via inheritance. That being said, when someone extends the styles, the link colors may not match as expected.