Microdosing is just under the threshold so my guess is that it actually does not have any effect at all and instead just a powerful placebo feeling.

That or that people are not microdosing at all so they are getting enough to start tripping lightly, experiencing some energy and euphoria.

Effects before they are epi-apparent. I think the effects are definitely measurable on a neurotransmitter level, but not so much on a sensory level.