Hibernate generates a deep copy of outbox event to check for dirtiness of the entity. The deep copy is done via serialiaztion and deserialization of the payload field - using io.debezium.outbox.quarkus.internal.JsonNodeAttributeConverter. During deserialization the Long nodes can become {Int}} nodes which means that the recorded state is different from the real one in logical JSON representation so the dirtiness is detected and UPDATE staements are triggered.

Setting the outbox entity to read-only solves the issue.