Quoting from https://stackoverflow.com/q/2769148/37994162#37994162
"As of June 22, 2016 Google Maps V3 no longer supports keyless access
so you need to get a key for every (referrer-)domain which has never
had a Google Map on it before."
Yet the code comment in config.php states:
this is not obligatory by now
The commit at https://git.netizen.se/RunnerUpLive/commit/?h=fix/require_gmaps_apikey updates the outdated comment.