there are no other abouts here 😄 a headliner is someone who is generally recognized
I doubt that someone would have to google who Dua Lipa, Shakira or Lady Gaga is.. even artists that haven't had a new hit in a while like Katy Perry or Pink people would recognize.. that is a headliner
headliner isn't someone with 1-2 hits in a specific country who you have to google to check who they are and what kind of music they do (Stormzy, I'm looking at you, yes)