For me this setting was off by default when I upgraded to Monterey

actually M$ do the same configuration for laptop. The graph card will be disabled while u unplug the power. So not matter what kind of the graph card u are using it will fallback to integrated graphics.

What a terrible idea to enable low power mode on battery by default.

I don’t think mine was enabled by default - I had to go in and turn it on after updating to Monterey. 2020 M1 Air.

For Pro users, maybe. But the average user will value battery life over frame rates.

Low power mode wasn't enabled by default on my machine.