“Did you see his presentation? He pulled a 720 on the CEO with those financial charts.” (Meaning: He performed a very difficult, impressive maneuver that few others could execute.)

This is the most confusing—and most common—usage of 720 in internet arguments and relationship advice.

for this number, like a certain game or a social media trend?

To call something a “720” in this context means it is elite, difficult, and shows mastery. If a gamer says, “Did you see that 720 no-scope?” they are referencing a spin move so fast and complex that it requires inhuman reflexes.