How history, selected items, and capture behavior work together.
macOS treats a paste you trigger differently from an app that reads the clipboard on its own. Because VanX is a clipboard manager, it needs to notice when you copy something even while another app is in front — so the system may occasionally let you know it is reading the pasteboard.
VanX is built to read as little as possible: while nothing is happening it only checks a lightweight change counter, which does not look at your clipboard contents. It reads the actual contents only when that counter changes — i.e. right after you copy something new.