When Suicide Squad: KTJL takes place in the Batman: Arkham timeline
Trailer dialogue and the appearance of some returning Arkhamverse characters indicate when Suicide Squad: KTJL takes place in the timeline.

Rocksteady is returning to its acclaimed Arkhamverse with the upcoming Suicide Squad: Kill the Justice League. The title focuses on Task Force X's mission to stop Brainiac from invading Metropolis. Although Brainiac's plans have yet to be revealed, the trailer reveals that he has brainwashed members of the Justice League (such as Superman, The Flash, and Batman) to do his bidding. Suicide Squad: Kill the Justice League will reveal Rocksteady's take on several DC characters for the first time, with interactions and glimpses in the trailer giving players clues about where the upcoming title takes place in the Arkhamverse timeline.
According to information currently provided by Rocksteady, Suicide Squad: Kill the Justice League takes place after Batman: Arkham Knight. The presence of characters in Kill Justice League (like Penguin) suggests they are noticeably older than they were in the last Arkhamverse entry. Cobblepot now appears to have long gray hair, indicating that the time jump may be more than a few years.
Suicide Squad: KTJL's Batman Trailer Offered The Biggest Timeline Clue

The Game Awards 2022's Suicide Squad: KTJL trailer reveals Kevin Conroy will reprise his role as Batman in the first installment The last time, posthumously. The trailer shows Suicide Squad coming face-to-face with a brainwashed Batman in the Arkham Asylum setting, which could lead to a challenging boss fight where players may face the characters they once had in Batman: Arkham Tactics used in the game of Tom. However, the biggest clue in the timeline is Harley Quinn referring to Batman by his real name "Bruce," referring to Arkham Knight's twist-filled ending in which his secret identity was revealed.
Batman's Return In Suicide Squad: KTJL Caused Some Confusion

The mention of Batman's alter ego has caused some confusion as to why people still know Bruce is still Batman after Arkham Knight. He was last seen activating the "Knightfall" protocol and feigning death at the end of that match, convincing Gotham that another hero had taken his place. Characters like Harley Quinn who still know his identity suggest that despite the caped crusader's dramatic ending, his efforts may be in vain.
What this means for Batman status in the Arkhamverse, and how Rocksteady plans to send off Kevin Conroy's iconic take on the character, has yet to be revealed. This dialogue, along with the appearance of some returning characters from the Arkham Universe, really makes it Make it clear that Suicide Squad: Kill the Justice League takes place after Arkham Knight. All of this means the title can answer questions Batman: Arkham fans have asked over the past eight years, and close some of the series' unanswered questions, while still expanding Rocksteady's universe and introducing players to new characters and locations .
MORE: How to enjoy the entire Batman: Arkham series in order