No, it’s not suspect in and of itself. Often you need to develop a new benchmark when solving a new problem. It’s common to see this in software engineering/CS

No, it’s not suspect in and of itself. Often you need to develop a new benchmark when solving a new problem. It’s common to see this in software engineering/CS papers too. Of course, one should always be critical of benchmarks, and there is an obvious opportunity for bias here that should be reviewed with care. But your phrasing suggests that this is unusual or actively suspicious, which it is not.