Covid in children, the mechanisms that regulate its severity have been discovered

What mechanisms are behind the Multisystem Inflammatory Syndrome (Mis-C) that attacks children affected by Covid? And what differentiates it from less severe and mild forms? A set of 100 proteins (137 to be precise) linked to the severity of the infection which, although rarely, can affect the little ones.
The discovery is contained in a study signed by the Murdoch Children’s Research Institute-Mcri and the University of Melbourne, Australia, published in Nature Communications.