How the Great Resignation can snowball and become a BIGGER problem?

We all heard of the Great Resignation phenomenon starting in America. According to US Bureau of Labor Statistics, resignations remained abnormally high since April 2021. Surveys done in other countries seem to indicate that this trend is catching on in other countries. Employers as far as Australia are fretting and bracing for a tidal wave of resignations yet to come their way.

So, what is the cause of this trend? What is going on?