I've just configured HTTP referrers restriction for my Google Maps API key. I use map on my website. The problem is when I open it using Chrome and monitor network using Chrome DevTool, I found an interesting request
https://maps.googleapis.com/maps/api/js/QuotaService.RecordEvent?XXXXXXX
Let's say the XXXXXXX was the rest of the URL which you can find it by yourself when did the monitoring like I did. So I just repeat this request and monitor my google map usage in API console and it was increased significantly.
The question is how could we prevent this attack?