What it says on the tin. I don't expect a qt6 program to rely on a singular qt5 library, so this feels like a typo, unless I'm missing something?
Yeah, that doesn't look intentional: qt6? ( dev-qt/qtbase:6[gui,widgets] ) !qt6? ( dev-qt/qtprintsupport:5[cups] ) dev-qt/qtprintsupport:5[cups] <- duplicate On a side-clarification for anyone that don't know, [gui,widgets] that the first dependency does enables qtprintsupport on qtbase (which is fine), while qtbase[cups] is typically not necessary unless this does something special.
Also, may want to consider just dropping qt5 entirely if want to simply the ebuild. Posted on gentoo-dev some time ago that it's time to do away with optional qt5 support.