doing copy by Ctrl-C in the Chromium browser gives a nasty popup menu which i can often quit but it even may currupt my KDE Plasma environment (using Ubuntu 18.04 LTS) .. the OS gives a notice some app is crashed, but Plasma continues .. the popup menu also shows an item "Disable this popup", but when i choose it (by mouse) another notice window comes, saying "You can enable URL actions later by left-clicking on the Klipper icon and selecting 'Enable Clipboard Actions'" .. but i can not find that option on my Ubuntu ..

it seems the clipboard action is hooked by some other clipboard module, and they interfere .. is it a bug ? is it an option / setting ? FireFox does not have this behaviour ..

I assume, the default shortcut for toggling clipboard actions is Ctrl+Alt+X. You can look it up (or change) in clipboard settings for shortcuts.