In my limited experience, yes and no. LOL!
I have an old shoulder rig that squeaks...I have holsters I have bought brand new and have not used them alot that don't. I have a brand new Diamond D Guides Choice chest rig for my 460 that the harness squeaks with just about every breath in and out.. (LOVE this rig!! By no means am I dissatisfied with it for this)
Leather can be squeaky. Especially when carrying heavier weapons. Also, holsters that are tighter fitting to your weapon seem squeakier than other types.. Example: A basic Hunter brand designed for just about any brand large frame revolver with a 4"bbl compared to a tighter fitting, more concealed carry oriented, make/model specific Bianchi 3-slot belt holster...
And as the leather breaks in and wears to your belt, revolver and body it should quiet down some....
All of this is just my experience.... Which compared to many others is limited.