Songfacts®:

• Though all the signs are that it's over, 5 Seconds Of Summer singer Luke Hemmings' won't close the door on the relationship. He forlornly hopes to salvage their love, but it's doomed to fail. This song specifies two "bad omens" that he should end the romance:
  
  His lover loves somebody else and keeps leaving him for her other man.
  
  When he kisses her, she just stares at the ceiling.
• 5 Seconds of Summer recorded "Bad Omens" for 5SOS5. They laid down much of the album at Joshua Tree in Southern California in November 2020, but this song came later. "A lot of the songs that we made were just on our own, and towards the end it was really fun to be able to fill in the gaps," the band told Spotify. "Like, we need a song with more tempo or whatever it might be, and this song was definitely that."
• Luke Hemmings and drummer Ashton Irwin wrote the song with:
  
  British songwriter/producer James "JHart" Abrahart (Martin Garrix's "Don't Look Down," Fleur East's "Sax," OneRepublic's "Didn't I").
  
  American singer-songwriter Sarah Hudson (Katy Perry's "Dark Horse," Iggy Azalea's "Black Widow," Dua Lipa's "Levitating"). She previously co-wrote 5 Seconds of Summer's Sounds Good Feels Good track "San Francisco."
  
  Los Angeles producer Jason Evigan (Demi Lovato's "Heart Attack," Maroon 5's "Girls Like You," Dua Lipa's "Physical"). He also co-wrote and co-produced another 5SOS5 track, "Me Myself & I."
• All four members of the band sang the gang vocals at the end of the song along with JHart. They recorded them together all in the same room rather than layering it harmony by harmony.