For years, Facebook has made the pitch to customers that its wealth of user data — from birthdays to favorite television shows — allows it to deliver the right ad to the right person at the right time. These capabilities helped Facebook, along with its rival Google, to take in most of the more than $100 billion in annual online ad spending.

But Facebook’s access to the data that powers this revenue model may be starting to dry up. Last year, a new rule in the European Union, the General Data Protection Regulation, forced internet companies to comply with stricter safeguards in handling user information. And as customers become more hesitant to share their own data, Facebook and other digital-media companies are moving to regain their trust through additional protections.

Now, some of Facebook’s efforts to appease critics who complain of discriminatory practices may further chip away at the model.

In the interview, Ms. Sandberg conceded that the changes could make advertising on Facebook less efficient for some customers who had used the targeting practices “in a very fair and nondiscriminatory way,” but added, “We believe that that was a cost well worth bearing.”

Under the new approach, Facebook will require advertisers in the areas of housing, employment and credit to use a separate portal that will not include gender or age as targeting options. It will also preclude selecting an affinity group of people interested in a race, ethnicity or religion. The company has generally allowed advertisers seeking to reach members of a race or religion to aim at such affinity groups.

The company will continue to allow advertisers in other areas to deliver ads on the basis of age, gender or any affinity groups.

Even in the less sensitive areas, advertisers can’t exclude groups associated with race, religion or ethnicity from seeing ads. They can only affirmatively aim ads at them.