[brikil]

The clipboard is accessible from the javascript runtime from any page in any tab. Maybe disabling paste is intended to discourage the behavior?

I think this is also why lastpass clears your clipboard a few moments after you click the “copy to clipboard” button.

[msbarnett]

JS has write-only access to the clipboard, for precisely this reason. It would be a security disaster if JS could snoop your clipboard.

Lastpass and other password managers like 1password wipe the clipboard after a few seconds to minimize native app access to the secret.

[toxik]

Sounds like a security issue in Javascript to me