Why does the SM concert venue look half empty? Did it get hit by a bomb or something and part of it is under repair?

SMコンサート会場はなぜ半分空っぽに見えるのでしょうか？爆弾か何かで被災して一部が修復中なのでしょうか？

https://video.twimg.com/ext_tw_video/1921072172854112256/pu/vid/avc1/360x640/LENPFBYl-g8CPCHr.mp4?tag=12