Mr Chen, I did a perfunctory search before posting and a more thorough one at your suggestion. The most recent thing that applies to my specific question was the two year old video that left the question about “yum yum yellow” pretty much hanging, and still didn’t address my question about DMs on boats requiring black or blue fins. Notice the references in Lorenzoid’s post are mostly a decade or so old.
I did read with interest about the instructor who specifically chose yellow fins so his students would be able to find him, and parenthetically I should mention that one of my DMs in Nassau chose white fins pretty much for the same reason. Here’s a picture of her clowning for the camera as she keeps watch over her charges.
I feel like my question has some legitimacy… and I still don’t have a definitive answer. I do know I like swimming in these fins much better than the stiff, open heel “boards” they replaced!