From Google:
https://blog.google/products/gmail/g-suite-gains-traction-in-the-enterprise-g-suites-gmail-and-consumer-gmail-to-more-closely-align/Quote:
Consumer Gmail content will not be used or scanned for any ads personalization after this change. This decision brings Gmail ads in line with how we personalize ads for other Google products. Ads shown are based on users' settings. Users can change those settings at any time, including disabling ads personalization. G Suite will continue to be ad free.
The value of Gmail is tremendous, both for G Suite users and for users of our free consumer Gmail service. Gmail is the world's preeminent email provider with more than 1.2 billion users. No other email service protects its users from spam, hacking, and phishing as successfully as Gmail. By indicating possible email responses, Gmail features like Smart Reply make emailing easier, faster and more efficient. Gmail add-ons will enable features like payments and invoicing directly within Gmail, further revolutionizing what can be accomplished in email.