The m68k-mint profile does not inherit base, another similar profile or declare important profile variables such as USE_EXPAND. As a result, the profile is pretty much useless and confuses pkgcheck a lot. One of the result is that all implicit USE flags are reported as unused on gentoo-ci [1]. [1]:https://qa-reports.gentoo.org/output/gentoo-ci/output.html#global
I've added base to parents, I hope that fixes it.
Yep, works good now.