Machine Gun Kelly
Started out doing rap and in general his rap music wasn't particularly well liked. The dude also infamously released a diss track aimed at Eminem which backfired big time, with Em releasing a counter diss track which many agreed was the superior song. In the past couple of years MGK switched from rap to pop-punk rock music heavily influenced by late 90s and early 00s acts like Blink 182 and early 00s Green Day and the general reception to his music has greatly improved, with the dude now earning a decent amount of praise and hell he even got one of his songs in the recent Tony Hawk's Pro Skater 1+2 remake.
The stage persona of singer Moriah Rose Pereira, Poppy was always a subversive act, but her early stuff stuck close to her namesake by being very "poppy" music. Still decent pop music, but starting with her second album "Am I a Girl?" she began to also show influences from industrial metal (especially noticeable with her collab with Grimes on "Play Destroy"). This would be taken further with her third album "I Disagree" which is far more influenced by the likes of industrial and nu metal, and it's even speculated that the uncredited feature on the song "Fill the Crown" is likely Marilyn Manson, who is in fact a fan of hers. It was also around the time of the third album's making that Poppy finally split from her emotionally abusive ex-manager (and possibly ex-boyfriend) Titanic Sinclair, signed with Sumerian Record, a label that mainly signs djent metal bands, and started a relationship with horrorcore rapper Ghostemane, so it's likely the split from Titanic means she's showing more of her true self in her recent music.