Most football fans know how corrupted FIFA is, and all of them don't give a fuck, so I'm sure people won't give a fuck that Madonna's performing in an event organized by a corrupted entity. Most football fans very often criticize FIFA for a whole multitude of reasons, they have for years, and it doesn't stop them from enjoying the sport or from enjoying the world cups.
So I'm not worried on that front. What is not corrupted in our day and age anyway? Apple just agreed to use israeli chips in their iphones... and that's one example among many.
Also Madonna is not a global niche artist, she appeals to people from all walks of life, she's sold millions of albums per album for over half of her career, the whole world knows at least one madonna song... let's be real, she fits this kind of global event. ESPECIALLY now that the general public seems favorable to her again.
The KPop group BTS is even less "suited" than Madonna is, let's be real.
Just a silly example but my mom, who's a big football fan alongside my dad was happy to tell me Madonna was to perform for the world cup. And that's the kind of response the general public is gonna have. "oh, these artists are gonna perform, cool" that's it