This since this is 419+ million user records mentioning: account ID, phone number, country and gender.
Who collected this information is unknown, but it was stored in the MongoDB database without a password set.
Facebook claims that the information in the database is outdated. They say it was collected before the social network turned off adding friends by phone number last year.
At the same time, the last entries in the database were uploaded in August 2019. And even if the data is from last year, it is unlikely that all 419 million users have already managed to change their phone numbers.