You recommended the work. They said not today. Then they vanished
A customer declines the brake job in March. The plan is to follow up. Nobody does, because chasing every declined RO by hand is a job no one has time for. By the time anyone thinks of them, they've had the brakes done up the road.
Declined work
The customer who used to come in every few months and just stopped shows up in the data as a gap that nothing acts on.
The lapsed customer is recurring revenue you already earned once.