This is actually even more puzzling than it seems, because the green part of the spectrum is the most energetic.

I've read elsewhere that photosynthesis is partially limited by dealing with free radicals, and at peak light flux, many plants would be damaged by the monoatomic oxygen species that light-capturing complexes would create. Hence pigments that reflect some green light.

Article:

https://www.quantamagazine.org/why-are-plants-green-to-reduc...