My neighborhood is lit by metal halide acorns, and I have witnessed in person a few of them go EOL before. A lot of the lamps change from a white color to a solid pink glow one day (or a few) before EOL.

Acually this was discussed may be a year ago or so. These lamps are likely sodium-scandium.

(1) Sodium / scandium balance changes over the lamp life, if the balance shifts to sodium by a chance, lamps turns pink.
(2) More likely, at EOL burners are seriously blackened, so more energy is dissipated inside, and temperature raises. As NaI and NaBr are hard to evaporate and have high boiling points, higher temperature again shifts salt vapor balance to sodium and the light to pink.

 

Here is the picture with the discussion .