• Deprecation
  • Tests (Add specs for deprecating multiple copies of the same variable flag sass-spec#1897)
  • Dart Sass (Deprecate duplicate !global and !default declarations dart-sass#1931)
  • Sass Site (Document the deprecation of multiple variable flags sass-site#716)
• Removal
  • Deprecation metadata ([Duplicate Var Flags] Mark as obsolete #4129)
  • Tests (Add specs forbidding multiple !global or !default flags sass-spec#2078)
  • Dart Sass (Forbid multiple !global or !default flags on the same variable dart-sass#2636)
  • Website

Currently, variable assignments can have any number of !default or !global flags. Multiple instances of the same flag don't do anything, though. They should be rejected by implementations.

Since this is technically a breaking change, it will need a deprecation period. The spec already requires at most one of each flag, so it won't need to be updated.