In 25w31a, the new Shelf block has:
“Item placed” appears when you insert minecraft:air into (= empty) one of the slots. It should be “Item taken” or “Item removed”.
“Item swaps” and “Items swap” appears when multiple items from the same stack are swapped. Should be “Stack swaps” and “Stack swaps”, or just always “Items swap”.
Technically patched in 25w31a.
Still present in 24w40a.
I honestly prefer the older ones, but the newer ones look more polished, which might be what Mojang intended to use. Whatever the intended palette is, I hope they can make it consistent before 1.21.2. I've seen they've updated the blaze texture (MC-144327) after 5 years, so it seems logical to fix it soon.
I made it clearer, hope it helps.
Can confirm in 1.21, even after the icons got separated from their main texture file.
I've added some more screenshots where it's more visible. You can notice how even the pivot point is technically wrong as it gets in the top part of the chest during the animation.
Can confirm for 1.17.1
Edit: Should be “Stack swaps” and “Stacks swap”, […]