Favourite button on community page header doesn't work

Can be reproduced on Firefox 65 and Chromium 72

Way to reproduce

1. go to community page (e.g. https://gitter.im/viktomas-godu)
2. click on the star button in the header

The star should become yellow and the community should be favourite. Instead nothing when you open console, you can see that the app tries to send POST request to non existent endpoint.