How do you know how many new engines it has had? I thought thus far we didn't have concrete data on how often SpaceX are swapping engines during refurb, which a

How do you know how many new engines it has had? I thought thus far we didn't have concrete data on how often SpaceX are swapping engines during refurb, which also means we don't have reliable info on how much it actually costs to refurb for each flight.