You have complete control over every aspect of your powers' manifestation. This means you can choose to leave no evidence of power usage, even to the most advanced analytical tools, or maybe even falsifying power appearances and traces, to match the abilities of others. All effects that are nonessential to the proper functioning of the power can be reduced from anywhere between their normal amount and nonexistence. For example, a telepath can engage in mental combat without revealing their identity, a blast of fire may leave no evidence besides the intense heat, and a tinker creation can mimic the work of another, at least in appearance.
Even in cases where it should be clear that power use is involved, you always have a chance to shift the circumstancesin a way that leaves room for reasonable doubt. While relentless and meticulous observer may eventually conlude you might in fact posess powers, determining their true nature or effects is as challenging as you desire, perhaps allowing you to deceive even those who would othewise lay claim to omniscience.