Abilities that in terms of pure power are
qualitatively superior to the physical stats of the character, e.g.
a physically Tier 7 character capable of casting a 1-A fireball, or hax which has potency
qualitatively superior to the baseline potency, e.g.
soul hax which can affect a character that
sees them as mere fiction.
The typical way for an ability to be proven as being smurf in the aspect is it having showings or statements of being able to affect a character, which it shouldn't due to them transcending them in a way that it would require such a higher potency to affect them.
A typical example would be affecting characters which see them as mere fiction. See here for details on why characters with certain transcendence resist certain things.
It's important to separate the case of Power or Potency from the case of Range or Area of Effect.
A higher-dimensional character might be immune to regular mind manipulation due to being outside its range, but not due to their mind being fundamentally infinitely harder to affect. Of course, exceptions may apply if there are statements or feats of the opposite.