Exterior shower leaking at connection

Exterior shower leaks at the connection point are almost always a worn washer or O-ring in the quick-connect fitting — cheap part, easy fix, and it's worth checking before assuming a bigger plumbing issue. If the leak is coming from behind the panel rather than the visible fitting, that's a different repair involving the supply line itself. Where exactly is the water coming from — the fitting itself, or from behind the exterior panel?