Have there been any studies about whether Dyson swarms harvesting under 0.1% of the star's output are detectable, especially if the designers want to minimize the chance of detection?

I suspect that civilisations that make it to the Dyson swarm stage are on average a little biased towards environmentalism in order to survive past their terrestrial industrial stage.

Doesn't make sense to put a giant target on yourself until you can discount the dark forest hypothesis either, especially not when you've just beaten incredible odds to become a near-immortal truly space-faring civilisation.