The ebuild does not require a dependency on gtk+[X], but does not build without it. Reproducible: Always
>emerge -pqv plymouth [ebuild R ] sys-boot/plymouth-22.02.122-r1 USE="drm gtk pango (split-usr) udev -debug -static-libs"
Created attachment 783329 [details] emerge --info sys-boot/plymouth emerge --info sys-boot/plymouth
Created attachment 783332 [details] build.log
I can confirm that this happens for me too, I've updated the dependencies to include [X] as part of updating the package: - https://github.com/gentoo/gentoo/pull/36091 this should resolve this hopefully