In real chemistry, a substance that improves a reaction somehow (speeds it up, slows it down, makes it happen in the first place) but is not consumed in the reaction is called a catalyst. It's not a cheat.

But, Minecraft is a game. The fun is, at its core, learning. Does building a powder-duping machine make the game more or less fun for you?

if you’re on a single player world, that’s up to you to decide! it’s your world, your rules. i personally consider it a bit broken so i don’t do it, but i also consider iron farms broken so my opinion is probably not representative.

if you’re playing on a server, consult with other players, or check the rules/ask admins if it’s a big server with established rules.

The devs have explicitly not patched it and even test to make sure it still works when they make redstone changes, while they have patched other methods in the past

I personally would consider it cheating, as it is unintended and a bug.

On the other hand, if it's your world or smth. You're the one making the rules, so it's up to you to decide.

Yeah I'm thinking of it's a protected bug and it is my own world I'm off to build a sand duper

I put it in the same category as TNT duping and tripwire hook duping.

If the game's code allows duping via a specific arrangement of blocks, it's not cheating :)

/give sand is cheating, but building a sand duper isn't.

NO for me, because I will not rebuild a farm/redstone contraption for the 3rd time because some online idiots lobbied a company into "patching" some mechanic IN A SANDBOX GAME because it's "overpowered"/"illegal".

Neither. It is an exploit of a bug, so not a legitimate farm, but Minecraft is not a competition, so it is not cheating.