That could certainly be the case. You would need a spectrometer capable of measuring duv, and use that over time. Or you could compare the output of an old emitter vs a new one. It’s not obvious with LED when color shift happens over time, unless you see a new emitter next to the old or something else catastrophic has happened like massive LLD. Case in point, Berkley, CA , where steep light lumen depreciation combined with substantial chromaticity shift resulted in the premature replacement of LED street lights. The old lights were 4000K and looked pretty close to Oakland’s lights, but in the picture you can see they look a lot more yellow. It was obvious the lights in Berkley were changing color, and people noticed. However, things ended up on a positive note for Berkley as they got an upgrade to brand new 3000K lights.