Welcome to the iNat forum!
I’m not convinced this is exactly a bug report as the site is designed to use google for maps and locations to run, so it is working as intended. It sounds like it might be better phrased as a feature request, though I’m not familiar enough to know what that request would look like/how it would be phrased - it seems like it might involve a serious amount of work to address the issue.
It looks like pihole allows for whitelisting. Can you edit the whitelist to allow iNat to run as desired?
The forum is a Discourse product, so I don’t think use of google domains here could be modified by iNat (though I could be wrong).