The legacy version of clean-css can remove attributes from SVG code.

That issue mainly highlights gulp-clean-css isn't updated anymore.

https://github.com/foundation/foundation-sites/issues/12537

There is a more recently maintained aptuitiv/gulp-clean-css fork.

We can try to contribute to https://github.com/aptuitiv/gulp-clean-css a fix to the last clean-css version to see if maintainer is reactive, and if so, adopt it. If not, we can fork it to nasqueron/gulp-clean-css or look if another fork is active (adding discussion to take a decision on this).