GoldenTests not matching local machine

[vanlooverenkoen]

When running Golden Test on a local machine

        return Shimmer.fromColors(
          child: Container(
               width: double.infinity,
               height: 48,
               decoration: BoxDecoration(
                  borderRadius: BorderRadius.circular(6),
                  color: baseColor,
               ),
          ),
          baseColor: baseColor,
          highlightColor: highlightColor,
        );

My basecolor has an opacity op 0.2 done with withOpacity(0.2) but this results in golden test differences when running the test on CI.

It would be nice to have some documentation on how we should be doing shimmer test?