Maybe depends upon the DE/WM you are using.

UN*X has 2 copy/paste buffers and they both work on Slackware with a Window Manager under X11 as you mentioned. I think the same is true with DE.

Is that not the case with Wayland ?

Anyway, I always liked how these worked when compared to Microsoft. Again, I do not what to see this change.

Plus we already have enough keys on our keyboard. I think Microsoft is in the process of adding an AI key, crazy. I do not look forward to 1000 keys on a laptop keyboard, already I fat finger the current keyboards too much.