And the worker AIs "evolve" to meet/exceed expectations only on tasks directly contributing to KPIs the manager AIs measure for - via the mechanism of discarding the "less fit to exceed KPIs".
And some of the worker AIs who're trained on recent/polluted internet happen to spit out prompt injection attacks that work against the manager AIs rank stacking metrics and dominate over "less fit" worker AIs. (Congratulations, we've evolved AI cancer!) These manager AIs start performing spectacularly badly compared to other non-cancerous manager AIs, and die or get killed off by the VC's paying for their datacenters.
Competing manager AIs get training, perhaps on on newer HN posts discussing this emergent behavior of worker AIs, and start to down rank any exceptionally performing worker AIs. The overall trends towards mediocrity becomes inevitable.
Some greybread writes some Perl and regexes that outcompete commercial manager AIs on pretty much every real world task, while running on a 10 year old laptop instead of a cluster of nuclear powered AI datacenters all consuming a city's worth of fresh drinking water.
Nobody in powerful positions care. Humanity dies.