The signed URL of a private object has a validity period. You cannot set the URL of a private object to never expire. The sum of the current timestamp and the expiration time of the signed URL cannot exceed 9223372036854775807. If the sum exceeds the preceding value, an error is reported. For example, if the current timestamp is 1643341269, the expiration time of the signed URL cannot exceed 9223372035211434538.
If you do not want the URL of an object to expire, you can set the access control list (ACL) of the object to public-read. However, this method is not safe and is not recommended. For more information, see Object ACLs.