If you mean this in a psychedelic context, my theory is the temporary dissolution of this “society” in recognising the “self” as “self”

I will try my best here...

Near every thought in your head is an abstracted away primal urge. Hunger, fear, security, etc - We justify and express these urges with our actions and thoughts and interactions each day. This mesh of impulses eventually creates patterns of behavior that form our identities.

We go about our lives viewing the world through the lens of this identity, with even our most selfless actions being driven by a reason derived from the rule set of the identity. This rule set is the "ego"

Ego death then is the temporary dissolution of the guiding ruleset of the identity. It is a self, without the self. You exist, but, often for the first time in your life, your mental and emotional rule set does not.

Often, without the blinders of the ego blocking a view of the world, a person experiencing ego death feels the unimportance of their existence - not in a bad way - but in a universal matter of fact state, shared by everything else. This is often the "awe" of ego death

Dissolution of a myth.