The 8-digit hexadecimal RGBA syntax is a more standard way to represent colors than the rgba() color function, which is CSS-specific.
The 8-digit hex notation is valid CSS as of the CSS Level 4 spec: https://www.w3.org/TR/css-color-4/#hex-notation
Additionally, the CSS rgba() comma-separated color function is considered *legacy color syntax* as per the CSS Level 4 spec: https://www.w3.org/TR/css-color-4/#legacy-color-syntax
Sass has built-in support for CSS Level 4 color notations: https://sass-lang.com/documentation/values/colors/
The 8-digit hexadecimal RGBA is a drop-in replacement for rgba() values in both CSS and SCSS, so this is functionally compatible if the file is used directly.
BREAKING CHANGE: drops CSS rgba() values in all output formats. It's a soft breaking change for CSS and SCSS outputs, but a hard one for JSON.
