饭圈 slang.
回踩 = 'to turn back and stomp' — the act of, after leaving a fandom (
脱粉), publicly bashing the idol you used to support, often weaponizing insider info.
狂魔 = 'crazed demon', a productive suffix for someone who does X obsessively (
拍照狂魔 'photo-taking demon',
加班狂魔 'overtime demon'). A
回踩狂魔 is the worst-case scenario for any star: a former stan who now exists to dunk on them daily.