So what you need to do is:
- Click on the name of the challenge on a page with a URL like https://maproulette.org/challenge/50062/task/276083977.
- That takes you to an identically named but different page https://maproulette.org/browse/challenges/50062.
- On that screen there is a small white icon (“a flag”) that you can click on
- On the next screen you have to enter an email address and some text. It says it will create a github issue.
- After doing so the white symbol to the right of the text at the https://maproulette.org/browse/challenges/50062 page changes from white to red and the text “This challenge has been reported” appears.
- Clicking on that goes to the github issue. It was opened by the repository owner and contains a link to the logged in OSM user.