It's related to Melody JKT48. She is one of the first generation members of JKT48. Among the others, people can easily recognize her since she frequently stand as the center.
As the "everlasting center", it's common for the audience to see her performing in almost every song. In Request Hour 2017 show, she sang many songs, as people thought. But the only uncommon thing was at the end of the show, she announced that she had decided to graduate from the group that had been her home for six years. The show was aired online.
People started to take her "picture" by pausing the video and shot the screen, they sent wishes to her and their shockness as well as their disbelief. I was also shock and sad, knowing that the amount of first members of JKT48 gradually decreasing.
Melody will be showing her last stage on March 24 2018. So long, Melody.