Use of new var

scss/_variables.scss

@@ -1293,7 +1293,7 @@ $form-range-thumb-focus-box-shadow-width:  $input-focus-width !default; // For f
 $form-range-thumb-hover-bg:                var(--#{$prefix}highlight-bg) !default; // Boosted mod
 $form-range-thumb-active-bg:               $primary !default; // Boosted mod: instead of `tint-color($component-active-bg, 70%)`
 $form-range-thumb-active-border:           $primary !default; // Boosted mod
-$form-range-thumb-disabled-bg:             var(--#{$prefix}border-color-translucent) !default; // Boosted mod: instead of `var(--#{$prefix}secondary-color)`
+$form-range-thumb-disabled-bg:             var(--#{$prefix}disabled-color) !default; // Boosted mod: instead of `var(--#{$prefix}secondary-color)`
 $form-range-thumb-transition:              background-color $transition-duration $transition-timing, border-color $transition-duration $transition-timing !default; // Boosted mod: no box shadow
 // scss-docs-end form-range-variables