Wrong copy/paste buffer used
With GNOME Shell 3.34.4 (Wayland) and GNOME Terminal 220.127.116.11, sometimes pasting something copied in Mozilla Firefox 74.0 (URL bar) or Thunderbird 68.5.0, the text formerly copied in another GNOME Terminal window is pasted instead.
The only way to work around it, is copying something new from a GNOME Terminal window, paste that in Firefox or Thunderbird, and then copy the wanted text, and then paste it into the GNOME Terminal.
It am not sure, how to force/reproduce this behavior. Currently it seems to happen randomly.