@sedition
The trope you're referencing has it so that people are clueless despite evidence of skill being presented, but in this one he intentionally hid his martial prowess. Remember, when they were attacked, it was entirely by use of Rocket launchers, used by someone other than him. The only two times he has publically used his cultivation at all, he 1: ran off to leave someone else to fight and 2: ended up getting eaten by a toad, after fighting one guy in a fight noone clearly witnessed.
Rather, the trope used here is "martial artist arrogance" [in that the Feng family can't imagine he has any skills to begin with], and that trope is common to nearly every single cultivation story out there, and thereby hard to avoid if you're into the genre. There's not (as I can recall) yet any narrative point wherein he clearly evidenced that he has anything more than basic cultivation.