Changed it to:
spec:
jobLabel: default-rabbitmq
selector:
matchLabels:
app.kubernetes.io/name: rabbitmq
namespaceSelector:
matchNames:
- default
I was looking at that a 100 times, I thought that app.kubernetes.io/name: rabbitmq
and name: rabbitmq
were equivalent.
Thank you so much to Joao on Slack for the pointer!