I’m going with clotshot failures but your 5G suggestion is highly workable as a factor. This is SKorea and every one of those kids is carrying a 5G phone. A half dozen of those things in close proximity could very well be creating a microwave field that could heat their hippyfied little bods up and the MRNA carbon could then do some damage-—like, oh, say 151 carcuses in the street?
I’m now reminded of that event in Texas last year ... very similar.