It would be great if there's an option in the Clipboard Applet to configure how long does the contents stay in the clipboard before it's erased. It would prevent to accidentally paste some ancient stuff (for instance big parts of text) a couple of days after it's not relevant any more. Reproducible: Always
I don't think that it's possible to accidentally paste ancient stuff. One needs to manually select elements from the history. The only automatic entry in the clipboard is the current one. On that one klipper doesn't have the control to really erase it as applications can set it.