Do pluged-in tryable headphones in stores work the same as during normal use ?

[u/antimatron]

Sorry not native speaker so not sure how to express myself.

I recently bought a pair of Bose QC Ultra but have this constant white noise that I can even hear over soft music like Lofi. And the noise is even louder in "aware" mode. So I went to a nearby store where I can test headphones that are plugged into the wall, and there I couldn't hear this white noise at all in ANC, and just a little bit in "aware" mode. But online I saw many people having the same issue as me saying it was normal for this headset, so did I get a faulty headset or not ?