The source – support.google.com
Business success has always depended on the strength of a company's relationship with its customers. This is especially important now, when privacy is so important and companies are moving away from user tracking IDs on the Internet.
To expand support for solutions based on direct relationships between customers, brands and publishers, Google will update the global tag (gtag.js) and Google Tag Manager (gtm.js). They will now create a new custom cookie on advertisers' domains to help them link conversions to ads more efficiently.
Like existing native cookies, the new file will receive a unique identifier. It will only be assigned to users on the site. From May 2021, this native cookie will enable more accurate conversion attribution, including when a user interacted with multiple ads before converting.
Advertisers can opt out of their own tracking cookies at any time. To do this, you must disable linking conversions in the settings.
As before, the business must provide users with accurate and complete information about what information it collects, and obtain consent to collect such data in accordance with the law.