The sandbox is automatically deactivated after 60 days due to GDPR regulations:
This is to make sure companies don’t keep employee data on sandbox after it was removed from the live account.
You can now extend the sandbox expiration by going to Settings-Sandbox-Delay auto-deactivation.
For example:
When an employee uploads a copy of their ID and they are a citizen of the EU, the company must delete the ID within 60 days.