Not only were they searching for it 17 years ago in 2366 on Tars Lamora, they said that they’d been searching for it for years already at that point.
The Protostar had been within Tars Lamora for 17+ years, and contained records of Captain Chakotay being in command of the Protostar with Hologram Janeway at his disposal, which would mean Chakotay was given the assignment sometime after Voyager returned to the Alpha Quadrant in 2378. Additionally, the ship’s files contain Holodeck programs with records of Odo, who would eventually serve on a Starfleet station and the bridge of a Starfleet vessel during the Dominion War, but not for another few years after we see it was abandoned in the past with the Diviner’s flashback scenes.
All these facts coexisting, and the record from Chakotay mentioning an anomaly, would be enough to cofirm some kind of time travel, but we also have direct confirmation from the author of the episode, Aaron J. Waltke,
in an interview released today.