Reference: https://docs.snowflake.com/en/user-guide/intro-key-concepts.html

Explanation
All Snowflake-managed keys are automatically rotated by Snowflake when they are more than 30 days old.
Active keys are retired, and new keys are created. When Snowflake determines the retired key is no longer needed, the key is automatically destroyed.
https://docs.snowflake.com/en/user-guide/security-encryption-manage.html#:~:text=All%20Snowflake%2Dman