What I’m noticing is that the bare spiral bulbs rarely go mercury starved but I’ve seem them on some occasions back when CFLs were popular, but I’ve noticed that the covered CFLs, such as the A19 and globe variants, tend to get dimmer and dimmer with age, they tend to start dimmer and lose their ability to reach brightness when the bulbs age.

Covered CFLs start dim when new but as they age they start dimmer and also lose their fully brightness. I’ve seen more covered CFLs glow the dull pink hue than bare spirals.

I think these getting dimmer because the tube is even more hot than in exposed tube CFLs as the phosphors degrades faster.