Some company called Aiplex has claimed ownership over BTS, Twice, and Blackpink videos which took them off YouTube for a few hours.
For YouTube, anyone can make a copyright claim and get videos taken down (if you can prove some sort of ownership like you posted the vid first or something) which is notoriously a horrible system.
Top girl group TWICE experienced a temporary shutdown of three music videos: “Likey” is the fifth most-viewed music video by a girl group of all time. “Like Ooh-Ahh” was the nonet’s debut single that currently sits at 280 million views. Meanwhile, their latest single “YES or YES” became the seventh-biggest 24-hour debut on YouTube at the time of its release. Jennie’s “SOLO,” PSY’s “New Face” and BIGBANG’s “Flower Road” and BLACKPINK "DU-DDU-DU-DDU" were missing from YG's channels.
And V's Singularity was also taken down :(
Luckily now all the videos are back up and the views are restored (though at first they were playing really low quality because they had to render again...)
“As soon as we found out the problem, we shared it with YouTube and solved it,” a representative from JYP Entertainment told Forbes. “We believed making the videos live again is the most crucial part, so we tried our best to make [them reappear] as soon as possible. While YouTube is still finding out the cause of this problem, it is good news at least that the videos are back right away.”