These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.62 s (backtrack: 0/20).


!!! Multiple package instances within a single package slot have been pulled
!!! into the dependency graph, resulting in a slot conflict:

kde-plasma/kwin:6

  (kde-plasma/kwin-6.6.6-r1:6/6::gentoo, ebuild scheduled for merge) USE="(filecaps) handbook shortcuts -accessibility -debug -gamepad -gles2-only -lock -screencast (-selinux) (-systemd) -test" pulled in by
    =kde-plasma/kwin-6.6*:6[X(+)] required by (kde-plasma/plasma-desktop-6.6.6-r1:6/6::gentoo, ebuild scheduled for merge) USE="handbook semantic-desktop -debug -ibus -scim -screencast -sdl -test -webengine" INPUT_DEVICES="-wacom"
    ^                ^^^^^^                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

  (kde-plasma/kwin-6.8.0:6/6::gentoo, ebuild scheduled for merge) USE="X (filecaps) handbook shortcuts -accessibility -debug -gamepad -gles2-only -lock -screencast (-selinux) (-systemd) -test" pulled in by
    >=kde-plasma/kwin-6.8.0:6 required by (kde-plasma/plasma-workspace-6.8.0:6/6::gentoo, ebuild scheduled for merge) USE="X fontconfig handbook ksysguard policykit semantic-desktop wallpaper-metadata -appstream -debug -flatpak -networkmanager -screencast (-systemd) -telemetry -test"
    ^^                ^^^^^^^                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      


It may be possible to solve this problem by using package.mask to
prevent one of those packages from being selected. However, it is also
possible that conflicting dependencies exist such that they are
impossible to satisfy simultaneously.  If such a conflict exists in
the dependencies of two different packages, then those packages can
not be installed simultaneously.

For more information, see MASKED PACKAGES section in the emerge man
page or refer to the Gentoo Handbook.


The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by kde-plasma/plasma-desktop-6.6.6-r1::gentoo
# required by =kde-plasma/plasma-desktop-6.6.6-r1 (argument)
>=dev-qt/qt5compat-6.11.2 qml
# required by kde-plasma/plasma-desktop-6.6.6-r1::gentoo
# required by =kde-plasma/plasma-desktop-6.6.6-r1 (argument)
>=dev-qt/qtbase-6.11.2-r2 wayland
# required by x11-misc/xdg-utils-1.2.1-r11::gentoo
# required by kde-frameworks/kf-env-6::gentoo
# required by kde-frameworks/kholidays-6.31.0::gentoo
# required by kde-plasma/plasma-workspace-6.8.0::gentoo
# required by kde-plasma/plasma-desktop-6.6.6-r1::gentoo
# required by =kde-plasma/plasma-desktop-6.6.6-r1 (argument)
>=app-text/xmlto-0.0.28-r11 text
# required by dev-libs/kirigami-addons-1.15.0::gentoo
# required by kde-plasma/plasma-workspace-6.8.0::gentoo
# required by kde-plasma/plasma-desktop-6.6.6-r1::gentoo
# required by =kde-plasma/plasma-desktop-6.6.6-r1 (argument)
>=dev-qt/qtmultimedia-6.11.2 qml
# required by kde-frameworks/qqc2-desktop-style-6.31.0::gentoo
# required by dev-libs/kirigami-addons-1.15.0::gentoo
# required by kde-plasma/plasma-workspace-6.8.0::gentoo
# required by kde-plasma/plasma-desktop-6.6.6-r1::gentoo
# required by =kde-plasma/plasma-desktop-6.6.6-r1 (argument)
>=kde-frameworks/sonnet-6.31.0 qml
# required by kde-plasma/plasma-workspace-6.8.0::gentoo
# required by kde-plasma/plasma-desktop-6.6.6-r1::gentoo
# required by =kde-plasma/plasma-desktop-6.6.6-r1 (argument)
>=kde-frameworks/prison-6.31.0 qml

!!! The ebuild selected to satisfy "sys-apps/accountsservice" has unmet requirements.
- sys-apps/accountsservice-26.27.3::gentoo USE="-doc -elogind -gtk-doc -introspection (-selinux) (-systemd) -test -vala -xcrypt"

  The following REQUIRED_USE flag constraints are unsatisfied:
    exactly-one-of ( elogind systemd )

(dependency required by "kde-plasma/plasma-workspace-6.8.0::gentoo[policykit]" [ebuild])
(dependency required by "kde-plasma/plasma-desktop-6.6.6-r1::gentoo" [ebuild])
(dependency required by "=kde-plasma/plasma-desktop-6.6.6-r1" [argument])