Stylelint has been bumped from version 13 to 15 at MDL-79003. Its configuration can be improved following migration guide outlined at https://stylelint.io/migration-guide/to-14 and https://stylelint.io/migration-guide/to-15, in particular:

• Using stylelint-config-standard-scss and stylelint-config-standard rule bundles.
• Differentiate file-type specific rules in .stylelintrc rather than in grunt config (potentially this can be expanded to other types if needed).
• Start using @stylistic/stylelint-plugin that has migrated the deprecated rules (or use https://github.com/prettier/stylelint-prettier)
• Add stylelint-no-unsupported-browser-features plugin (css only), so it will tell us if there are support issue, so we will have some browserlist awareness earlier.