This Purge Event is very important for anyone who does Influencer Marketing.
On December 14th, 2018 YouTube began deleting every account that that met their definition of “spam.” This was done to combat fake users, and inflated subscriber numbers.
Most of the larger channels were hardly affected and were able to recover in just a few hours. However, many channels having fewer than one-million subscribers suffered dramatic losses.
Check out the linked LINKED article to see the top 100 affected channels.