In version 2.23.1 when I set initialReplayIdMap to a value when the route starts everything behave like normal and I am fine with the replays. I'm getting an issue every time the route re-subscribes it tries to replay from the map again. The initialReplayIdMap needs to zero out (don't see any code that modifies the initialReplayIdMap) so we can default to -1 so we can wait for new replay ids. Eventually if i leave the route on for over 24 hours it eventually breaks because the replay id 24h time to live and the push topics stops working.
Something must have happened in Salesforce cause I saw the same issue in the salesforce java forcedotcom/emp-connector . The issue was reported and fixed here.