Kitchen counter LEDS are faulty- uniformly dim

[SUNRAY]

It's also a tell tale sign of a chromacity shift towards yellow, due to lower currents...

Thanks, that is what I have found when playing with COBs, especially when viewed out of the light beam.

But this

If the photo shows the true colour of the LED (yellowy slightly green light output), then the phosphor has degraded. Pretty common at that age and will need replacement.

is something I have not encountered or heard of before, which I readily accept as a schoolday.