Why Can't an Encrypted HLS Video Be Played After Being Transcoded for the Second Time?

The possible cause is that the key cache is configured on the encrypted HLS server. The Key Management Service (KMS) can cache the queried key locally. When another playback device requests the key next time, KMS can directly return the key without obtaining the key from the VOD service each time. Therefore, if the decryption key changes after transcoding, the cache needs to be cleared to obtain a new key.