Everyone thinks UX means "make the app look nice."
It doesn't. That's UI. UX is the part nobody sees: why the screens are in that order, why the form has three fields instead of seven, why people actually finish the thing instead of rage-quitting halfway.
So before you hire a UX designer, get clear on what you're buying. I match clients with designers for a living, and the single most common mismatch I see isn't skill. It's role. People hire deep researchers when they needed a pixel person, or a visual designer when they needed someone to fix a broken flow.