about the performance though, because they're singing live Riho goes into her lower register.
as a main vocalist in the whole song it just makes it sound off. also zukki's mic is louder making it sound lower that normal.
sayu is also a main vocalist in the song, but she lip sings or talks most of her lines and struggles live hence why the song sounds different live.
also since masaki is crying most of the time this is another factor involved.