What is the meaning of Matthew 17:12?

* The two F.O.G. Bibles & Commentary below are currently a work in progress.

But I tell you that Elijah has already come, and they did not recognize him, but have done to him whatever they wished. In the same way, the Son of Man will suffer at their hands.”

Berean Standard Bible (BSB)

but I tell you that Elijah has come already, and they didn’t recognize him, but did to him whatever they wanted to. Even so the Son of Man will also suffer by them.”

World English Bible (WEB)

But{G1161} I say{G3004}{(G5719)} unto you{G5213}, That{G3754} Elias{G2243} is come{G2064}{(G5627)} already{G2235}, and{G2532} they knew{G1921}{(G5627)} him{G846} not{G3756}, but{G235} have done{G4160}{(G5656)} unto{G1722} him{G846} whatsoever{G3745} they listed{G2309}{(G5656)}. Likewise{G3779} shall{G3195}{(G5719)} also{G2532} the Son{G5207} of man{G444} suffer{G3958}{(G5721)} of{G5259} them{G846}.

Strong's King James

(12) but I tell you that Elijah already came and they didn't recognise him, rather doing in his case whatever they wished. In this way also the Son of Humanity is going to suffer by them."

The F.O.G*

[12] But what they've missed is that Elijah has already come! The religious leaders failed to recognize him and mistreated him severely. Similarly, they will make the Son of Man suffer."

The F.O.G Paraphrase

and I say to you—Elijah did already come, and they did not know him, but did with him whatever they would, so also the Son of Man is about to suffer by them.’

Young's Literal Translation