The gwtoolsetUploadMediafileJob contains non-scalar value in it's parameters, the partner-template-name property is an instance of Title , thus it's serialization relies on the redis-base JobQueue ability to use PHP serialization.
The kafka-based queue deliberately doesn't support PHP serialization and requires all the jobs to be JSON-serializable per T161647, so the gwtoolsetUploadMediafileJob job should be changed and made JSON-serializable.