The detail_placement_view detail_placement_view is not intended to be used for campaigns with an advertising_channel_type PERFORMANCE_MAX, as this view is only intended to be used with campaigns containing ad groups, and Performance Max campaigns are constructed with asset groups rather than ad groups. However, this view is currently returning impression data for Performance Max campaigns. The impression metrics returned from the detail_placement_view may not be accurate and should not be relied upon for campaigns with advertising_channel_type of PERFORMANCE_MAX.
In the next release of the Google Ads API, v18, we will be adding a new resource called performance_max_placement_view, which can be used to query placement impression data for Performance Max campaigns, and in a subsequent release, we will stop returning impression data from the detail_placement_view for campaigns with advertising_channel_type of PERFORMANCE_MAX. Once performance_max_placement_view is released, use the data returned from that view for Performance Max campaigns rather than the data returned from the detail_placement_view.
If you have any questions or need help, check out the Google Ads API support page for options.
