SUMMARY
On my desktop I have plasma 5.27.11, on my notebook I upgraded to 6.0.5. 
The clipboard settings are (visually, in the GUI) the same, but the behaviour on 6.0.5 changed.

Selecting text  (X11 Primary Selection) appears in the history on 5.*, while it no longer does on 6.* unless I activate the option to keep the clipboard and selection in sync, which I do not want.

There is an option, but it only becomes editable if the sync is enabled, and doesn't allow me to configure it the way 5.* behaves (or I didn't find out how)

Please fix this regression, as managing both the selection and the clipboard content is an important usecase to me.
I also don't see why this should not be possible option-wise, as in: why this specific combination can't be configured.

STEPS TO REPRODUCE
1. Update to Plasma 6.*
2.  Use X11 (potentially same in Wayland, didn't test, not sure about selection there in general)
3. Mark text with mouse

OBSERVED RESULT
Text doesn't appear in clipboard history

EXPECTED RESULT
Text does appear, as it did in 5.*

If you think this is confusing for users, please at least offer an option (since the GUI seems somewhat prepared to that) to change that behaviour.