Before the find_package-call I used set(QT_NO_CREATE_VERSIONLESS_TARGETS TRUE). Then I created a library target which then links to Qt6::WebEngineWidgets. This then breaks the build with

The link interface of target "Qt6::WebEngineCore" contains:

    Qt::Core

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

b/c Qt6WebEngineCoreTargets.cmake uses the unversioned targets in its INTERFACE_LINK_LIBRARIES:

INTERFACE_LINK_LIBRARIES "Qt::Core;Qt::Gui;Qt::Network;Qt::Quick;Qt::WebChannel;Qt::Positioning"

Manually patching the file reveals other targets with the same problem. So as it is right now, the switch cannot function as intended.