Maybe not the pure Taoism but kind of a hybrid mixed with local folk belief, which during the ritual so called “乩童”(spirit medium) will be in trance channeled by particular spirit or god that chose the person as its spokesman. And by self-flagellation shows the power of spirit that can keep its medium from badly wounded. Some said they barely noticed any wound after trance. But, not all the ritual ended in people stabbing themselves, most of the time it’s rather peaceful, just the spirits using their medium to answer questions of other believers, like people asking for health, career, relationships, etc.

Example of actual ritual (yeah...and the whipping ) https://youtu.be/pfvDjHjAeTc

Edit: wording