I'm using the geolocation_googlemaps module to add a location field for an event content type. It is rendered in the backend to choose a location and in the frontend to show a map with the chosen location to the user. Recently, it stopped working. It is still possible to choose locations in the backend, but in the frontend the generated request to Google Maps gives a 403. However, when copy-pasting the URL to the browser, it works. The issue is not related to a restriction of secure/insecure content mixing, because the URL adapts automatically with in the beginning. The issue is that Google changed its usage and billing policies. The module uses the Google Maps Static API, which could be used without an API key up to now, but now every maps API needs such a key. Google writes about this here: https:developers.google.com/maps/documentation/maps-static/usage-and-billing

So in order to get a key and to get it into the Drupal module, follow these steps. First, go here https://code.google.com/apis/console and create a project. Go to the APIs and search for the Maps Static API. Create a key and restrict it to the Static Maps API and the referring domain(s) which should be able to use it. In the dashboard, add a payment method. Second, copy-paste the API key to /admin/config/services/googlemaps. When reloading the page, everything should work again.

An alternative is to switch to open streetmap. There are Drupal modules in place including geolocation and leaflet. I'll check these out later.