Traffic from your ads served on AdSense or Google Ad Manager.
Referrals from googleads.g.doubleclick.net are clicks on your ads showing on the Google Display Network—specifically, ads showing on publisher sites in the AdSense program—for which the destination URLs have not been tagged.
If you notice googleads.g.doubleclick.net appearing in your reports, check to see if auto-tagging is turned on in your Google Ads account, and that your own campaign variables are labeled correctly.
Similarly, referrals from tpc.googlesyndication.com are clicks on ads showing on the Google Ad Manager network.
