en.wikipedia.org/wiki/Trebonianus_Gallus

The article places the burning of the Temple of Artemis in the narrative of Trebonianus Gallus’s reign and immediately before events in early 253. But the cited event is generally dated to 262 CE, nearly a decade later.

A HISTORY overview of Ephesus states plainly: “In 262 A.D., the Goths destroyed Ephesus, including the Temple of Artemis.” That date falls well after Trebonianus Gallus died in August 253.

A sourcebook text of Jordanes, History of the Goths places the same attack specifically in the reign of Gallienus (260–268 CE): while Gallienus was emperor, Gothic leaders crossed into Asia and “set fire to the renowned temple of Diana at Ephesus.”

So the problem is not that Ephesus was never attacked, but that this article assigns the famous destruction of the temple to the wrong period. The raid belongs to the reign of Gallienus, not to the reign of Trebonianus Gallus.