Kind of weird to call it a "callback." I think the author just didn't quite know what to call it when Rings of Power is just taking straight up stealing scenes from the books an entire Age before they happen?

I don't think there is a name for it, because it's stupid and no one thought it was a good idea before now. Some marketing bozo heard book nerds were salty about Tom Bombadil not being in Jackson's movie and figured they paid for the rights, just rewrite the scene to fit?