What I’ve noticed, is that triphosphor fluorescent lights tend to glow pink when mercury starved (whether it’s CFL, T8, T5, or triphosphor T12). When they get so mercury starved, they just glow a dim pink color. While halophosphate bulbs (like the mercury starved Sylvania F34T12s at the library), become a dim purplish hue when mercury starved and this is true for almost every halophosphate fluorescent lamp. I’ve also seen the F15T8s mercury starved before, and those also turn a dim purple, I remember seeing a mercury starved GE Indonesia-made 15W cool white at an Airbnb, and it also had that dim purple hue, so this applies to any bulb using halophosphate.

I know argon is purple, so does triphosphor turn red when exposed to argon? I know the purplish hue on the halophosphate lamps is due to argon.

Depending on the gas filling and phosphor formulation. In halophosphate tubes, only the gas filling glowing when mercury starved. In triphosphors tubes, some of the red and also the green phosphors, glowing from the argon UV radiation as well.