This issue is a variant of Justice League (DC, 2018 series) #14 [Jim Cheung Cover].
Cover does not feature title logo
Shayera Hol, now the Empress of Thanagar Prime, is the wife of the "late" Katar Hol, the previous incarnation of Hawkman Carter Hall. Kendra is confused because she is supposed to be the reincarnation of Shayera, so she doesn't understand how they could both exist at the same time and place. Katar Hol reappears later in the story and is referred to as "The Savage Hawkman" and his costume is the one worn in The Savage Hawkman (DC, 2011 series). The explanation for this is revealed in issue #16.
J'onn refers to how he lived on Thanagar Prime for a while masquerading as a Thanagarian as shown in Dark Nights: Metal (DC, 2017 series). He explains that the reason he was on Thanagar Prime was to meet with The Keep, the living repository of all Martian history, and he was caught there when the war with the Dark Multiverse broke out.