The entire movie was shot during lock down in South Africa.
The entire film was shot on cellphones by the cast themselves.
The actors sent every line as a video clip and then the editor had to put it together to make it look like they were actually on a video-call communicating.
The actors didn't know "who did it" until the very last scene. The director got everybody together on a zoom meeting and improvised the scene. So the reactions you see in the last scene of the film are authentic reactions.