If you want to know this information, it would be stupid to just read the press release. This information is contained in a privacy policy, which is much more detailed than a press release, which never contains details like this which - let's be honest - most people don't give a shit about.
Persona's privacy policy is here. It does not cover selling your data to reddit or any other company - which means that under EU and California law, doing so is not legal. It does say it will share your data among affiliates such as to "archive" it - but I don't really see the issue with that specifically. The fact that your personal data is sitting in an Amazon S3 bucket is not of itself a problem, except if there is a problem with S3. You're exposed to similar risks if Persona keeps all the data itself.
Because nothing protects children more than uploading their selfie or government id to a random company who "promises" to delete the information seven days later .. because of course it will and everyone will be able to check and see the pink unicorn in person.