You can use the shorter .be url – just only copy up to (not including) the question mark.

If you’re disinclined to endure any inconvenience, you can put this in a userscript to strip the tracking code automatically (including what the copy button saves):

const listener = new MutationObserver((mutations, observer) => {
    // query blindly until found - it's never listed as an addedNode
    const field = document.querySelector("#share-url");
    if(!field) return;
    field.value = field.value.split("?")[0];
    // SPA and navigation events/functions not catching anything, so just listen forever :/
    // listener.disconnect();
});
listener.observe(document.body, {childList: true, subtree: true});