This was a performance that celebrated the dictator's birthday, as a national holiday no less.

Apparently he was having no negativity on his birthday.

https://www.newsweek.com/kim-jong-un-firing-squad-conductor-1590226
Byline: Journalist Joo Seong-ha, who writes for the Dong-A Ilbo daily paper.

...the story began on February 16, which is Kim's birthday. North Korea celebrates that date as the Day of the Shining Star, and Kim and his wife appeared at the Mansudae Arts Theater in Pyongyang for a night of performances to mark the holiday.

Joo wrote that one of the shows performed that night was called "Shadow Magic," which featured actors doing magic tricks behind screens as if they were literally shadows. Afterward, Kim reportedly praised the production, but a conductor remarked to someone nearby that he didn't think the show was all that good. Later that night, Joo wrote, the conductor was arrested.