A new fraud service must process the last 5 days of payment events, which other services already consumed. Which setup makes this straightforward?

Kafka keeps records for the whole retention period, even after other consumers have read them. A new consumer group with auto.offset.reset=earliest starts at the oldest record. So it reads all the stored history, and 7 days of retention covers the 5 days you need.

"A RabbitMQ classic queue with a long message TTL" is wrong. A classic queue deletes a message once a consumer acknowledges it. TTL (time to live) only limits how long an unread message waits. It cannot bring back messages that were already consumed.

"Redis Pub/Sub with a new subscriber" is wrong because Redis Pub/Sub stores nothing at all. A new subscriber only sees messages sent after it joins.