I noticed the issue while using the Docker container, but my guess is that this is generally an issue in regard to the advertised supported Java version for users of any Debezium publication and product. However, since the Java version in the container is chosen by us we at least can fix it here on our own.

[...]
java.lang.UnsupportedClassVersionError: io/debezium/connector/db2as400/As400RpcConnector has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0
[...]
java.lang.UnsupportedClassVersionError: io/debezium/connector/db2as400/smt/RepackageJavaFriendlySchemaRenamer has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 55.0
[...]

I couldn't find such an issue in the 2.5.x images I tried, but I found such issues in all 2.6.x images.

Maven is notorious to not resolve dependencies consistently and it doesn't know anything about the Java version requirements. Hence, there's no way to (that I know) to fix this during build time of Debezium. Afaik only switching to Gradle would make it possible to surface such issues. But, only if the libraries actually include the necessary metadata, which I doubt they do since they're most probably built with Maven as well.