Bug in ElastiCache when migrating from Redis to Valkey

Hello.

I tested it on my AWS account.
I changed from ElastiCache Serverless Redis OSS to Valkey (7.2) by following the steps in the following document.
After that, I switched from Valkey (7.2) back to Redis (7.1) and then upgraded again to Valkey (7.2).
As a result, I got the same error as you, and although the version was changed to 7.2, the engine remained Redis.
https://docs.aws.amazon.com/AmazonElastiCache/latest/dg/VersionManagement.HowTo.html

When I checked from the AWS CLI, the engine was still Redis.

~ $ aws elasticache describe-serverless-caches
{
    "ServerlessCaches": [
        {
            "ServerlessCacheName": "test",
            "Description": " ",
            "CreateTime": "2025-09-23T12:19:45.992000+00:00",
            "Status": "available",
            "Engine": "redis",
            "MajorEngineVersion": "7",
            "FullEngineVersion": "7.2",
            "SecurityGroupIds": [
                "sg-1234567"
            ],
            "Endpoint": {
                "Address": "test-12345.serverless.apne1.cache.amazonaws.com",
                "Port": 6379
            },
            "ReaderEndpoint": {
                "Address": "test-12345.serverless.apne1.cache.amazonaws.com",
                "Port": 6380
            },
            "ARN": "arn:aws:elasticache:ap-northeast-1:123456789012:serverlesscache:test",
            "SubnetIds": [
                "subnet-1234",
                "subnet-5678"
            ],
            "SnapshotRetentionLimit": 0,
            "DailySnapshotTime": "14:30"
        }
    ]
}

When I checked the version etc. from redis-cli, I found that it had been changed to Valkey internally.
So this may be a display issue in the Management Console or AWS CLI.

test-12345.serverless.apne1.cache.amazonaws.com:6379> info
# Server
redis_version:7.2
server_name:valkey
valkey_version:7.2
redis_mode:cluster
os:Amazon ElastiCache
arch_bits:64
run_id:0

# Replication
role:master
connected_slaves:1
slave0:ip=test-12345.serverless.apne1.cache.amazonaws.com,port=6380,state=online,offset=0,lag=0

# Cluster
cluster_enabled:1

If you experience issues like this, I recommend reporting them to AWS Support or via the Feedback tab in the bottom left of the Management Console.