- Open the visual editor or 2017 wikitext editor on a page on Wikidata.
- Click on the help button near the top right of the editor.
- Click on "Leave feedback about this software"
The dialogue in question says throughout that it's going to leave the feedback at VisualEditor/Feedback on wikidata.org, which doesn't exist. However, this is merely a display glitch, as the feedback is correctly posted on VisualEditor/Feedback on mediawiki.org as expected.