According to testing Screen tearing only works for wayland + vulkan application.
QT_LOGGING_RULES="kwin_*.debug=true"
To test the tearing you’ll need to add this environment variable
and then in console write this
journalctl -f | grep "Presentation"
And it should show Async that means tearing enabled on the app. (you’ll have to run the game)
Tearing doesn’t work on xwayland app.