As you saw, Momometal making her first appearance on video as the newly revealed 3rd member of BABYMETAL. This is the unfinished version of 'The One' (just the first verse). This is the song written as a tribute to and dedicated to the fans (also named The One of course).

You're sort of right about what happened with the lineup. Originally, there were three members, Su-metal, the lead vocalist, who is still there, Moametal, backing vocals and dance, who is also still there, and Yuimetal, backing vocals and dance, who retired from the group in 2018. From 2019, Momoko Okazaki performed with them as a support dancer, filling in Yuimetal's position in the dance formation. At Babymetal Begins in April 2023, Momoko was announced as the new member of the group and became Momometal. This performance was released just after Babymetal Begins, so Momometal had just officially joined the group and this was her first official appearance on video. As you may know, "The One" is the name given to Babymetal's fans. When Babymetal first started touring internationally, they noticed that many fans in the crowd were singing along and they were very touched that fans had learned the Japanese lyrics, so they wanted to reciprocate by singing a song in English for the international fans. This song is Babymetal's tribute to the fans, expressing their appreciation for their support. They don't play it live all that often, and when they do it always feels like a special occasion.

👍👍Thank your BABYMETAL for all the love you show The One. 🦊🦊🦊 🖖❤

Another re-upload.🦊🤘🔥

Your autotune-example wasn't autotune but reverberation applied to the voice. Also a method to even out slight "vocal problems". But autotune (nromally) corrects the frequencies and, when overdone, adds a weird effect to the voice. Hence it's often appied in this way these days: kzfaq.info/get/bejne/j55npqeE09iue5s.html

f you pause in the middle of a song, you should rewind a bit before playing it back. Respect the lyrics and the artist.