I suspect the throttling behavior has to more do with the power settings used during testing or OEM tuning on specific models.
https://www.youtube.com/watch?v=ymoiWv9BF7Q
In this video, they show the perf/watt curves at 8:30. And they show the on-battery vs on-wall performance at 18:35 across a wide variety of benchmarks, not just Geekbench. They used a Lenovo YOGA Air 15 on Window 11's "Balanced" power plan for their tests. The narrator specifically noted the Macbook-like on-battery performance.