Copy on select is the bane of my existence. I use selection as a reading aid, to follow where I'm looking and to help me focus. I do this in the terminal all the time. If it clobbers my clipboard, this does _not_ help me.
PRIMARY: Copy by select, paste with middle click or shift-insert.
CLIPBOARD: Copy with explicit copy action, paste with explicit paste action (mostly ctrl-c/ctrl-v, except in terminals/vim)
I'm not sure if this is carried over into Wayland. I've seen some Mac terminals offer copy on select and there it does clobber the clipboard, unlike on Linux.
Vim exposes these as the * (PRIMARY) and " (CLIPBOARD) buffers