Good news — a fix for the paste behavior in the email editor has been deployed. You should now be able to paste both plain and formatted text without issues.
If you’re still seeing anything on your end, a couple of quick tips that can help: use Ctrl+Shift+V (or Cmd+Shift+Option+V on Mac) to paste as plain text, or paste into your browser address bar first to strip formatting, then re-copy and paste into the editor.
Give it another try and let us know if everything is working as expected. Happy to help if you run into anything else!