https://people.com/music/american-idol-katy-perry-falls-audition-gas-leak/

ABC shared a preview of Sunday's episode that was interrupted by a gas leak. "Do you guys smell gas? It’s pretty intense," Perry says. "We’re getting heavy propane," adds Luke Bryan. Everybody had to be evacuated from the audition building.

I think she faked that she was ill otherwise she would have been rushed to the hospital.