[5] On April 14, 2022, a concept teaser was released via iKon's official YouTube channel and other social media accounts.

The accompanying music video for the title track, "But You", was released at the same time on iKon's official YouTube channel.

The sixth track "At Ease", which was previously performed by iKon on Kingdom: Legendary War, was exclusively made available on CD only.

iKon's label mates from YG, Mino and Yoon, members of the South Korean boy band Winner, co-wrote and co-composed one song each.

[12][2][9] Flashback debuted at number 2 on the Gaon Album Chart in South Korea, selling 99,918 copies.