You're referring to selection1, not the clipboard. There is (for me, on Arch) also a selection2, which I haven't investigated further. Notably Ctrl+C/Ctrl+V op

You're referring to selection1, not the clipboard. There is (for me, on Arch) also a selection2, which I haven't investigated further. Notably Ctrl+C/Ctrl+V operate on the clipboard, while selection and middle-click operate on (at least) selection1.