Beginning 
the week of Mar 4th, 2020, Shopping ads (both Product Shopping ads and Showcase Shopping ads) in your 
standard Shopping campaigns that target the Google Display Network will be 
eligible to appear on Gmail in addition to YouTube and 
Google Discover. This means that reporting information will include Gmail in addition to YouTube and Google Discover for the following configurations:
To allow your advertisers to 
opt-in/opt-out of Gmail, YouTube and Google Discover for standard Shopping campaigns, you will need to enable or disable the following setting:
  - Google Ads API - Modify the NetworkSettings of the standard Shopping campaign and set 
target_content_network to true (opt-in) or false (opt-out). 
  - AdWords API - Modify the NetworkSetting of the standard Shopping campaign and set 
targetContentNetwork to true or false. 
If you have any questions or need help, please contact us via the 
forum.
 - Ian Ballantyne, on behalf of the Google Ads API Team