Just spitballing here - but could you alter the opacity mask in the lumen scene only, as to make the leaves thinner and more stochastic samples will pass through?
Edit: I tried it myself by altering the material in lumen card captures as well as with the raytracing quality switch but didn’t really see any change in overall brightness level - however I don’t seem to be getting over-occlusion in the first place. Probably still worth a try.