Facebook blog:

We’re shutting down the Face Recognition system on Facebook. People who’ve opted in will no longer be automatically recognized in photos and videos and we will delete more than a billion people’s individual facial recognition templates.

and:

This change will also impact Automatic Alt Text (AAT), which creates image descriptions for blind and visually-impaired people. After this change, AAT descriptions will no longer include the names of people recognized in photos but will function normally otherwise.

As to why, Facebook says:

We need to weigh the positive use cases for facial recognition against growing societal concerns, especially as regulators have yet to provide clear rules.

On that last, consider this from The New York Times coverage:

When the Federal Trade Commission fined Facebook a record $5 billion to settle privacy complaints in 2019, the facial recognition software was among the concerns.

And:

Last year, the company also agreed to pay $650 million to settle a class-action lawsuit in Illinois that accused Facebook of violating a state law that requires residents’ consent to use their biometric information, including their “face geometry.”

So, yeah, that’s got to be part of the calculus.