Good breakdown on this in arstechnica:

arstechnica.com/?p=1991469

In a statement emailed to Ars Technica, Cox Media Group said that its advertising tools include “third-party vendor products powered by data sets sourced from users by various social media and other applications then packaged and resold to data servicers.” The statement continues:

Advertising data based on voice and other data is collected by these platforms and devices under the terms and conditions provided by those apps and accepted by their users, and can then be sold to third-party companies and converted into anonymized information for advertisers. This anonymized data then is resold by numerous advertising companies.

The company added that it does not “listen to any conversations or have access to anything beyond a third-party aggregated, anonymized and fully encrypted data set that can be used for ad placement” and “regret[s] any confusion.”