Google is blocking duplicate Lookalike audience lists
via ads-developers.googleblog.com
Short excerpt below. Read at the original source.
A quiet but important change is coming to the Google Ads API that will affect how advertisers and developers create Lookalike user lists — particularly those running Demand Gen campaigns. What’s changing. Google will begin enforcing a uniqueness check on Lookalike user lists, preventing the creation of duplicate lists that share the same seed lists, […]