Duplicant receives sunburn while shielded from light

This is because the animation doesnt show the real location of the dupe. I would guess the middle tile is where the dupe actually is when using telescope

When they get off the telescope, they move to the middle tile before they start walking. I also suspect it is the middle tile.

In any case, it is arguably a balance mistake that duplicants can't do telescope research without getting sunburn. The vanilla telescope protects duplicants from this, but the Spaced Out telescope doesn't.