The default.php within the tmpl folder needs to be updated to api v3 of Google Maps.
Change
to
at line 34
Add your own language code, mine is 'nl'
Result:
<script async defer src="https://maps.googleapis.com/maps/api/js?key=<?php echo trim($params->get('googleapikey'))?>&language=nl" type="text/javascript"></script>
Also sensor is no longer supported, but that should not give any problem if it works well:
<script src="https://maps.googleapis.com/maps/api/js?sensor=false&ver=1.0" type="text/javascript"></script>
You might need to update your API at
cloud.google.com/maps-platform/
and add a billing program in order to get it to work again.