Why is the ultraviolet germicidal lamp lavender?

Ultraviolet light itself is invisible. If the ultraviolet germicidal lamp does not emit light,

Then we don't know if the ultraviolet germicidal lamp is on or not.

Long-term exposure to ultraviolet rays is harmful to the skin, from rough skin to skin cancer.

So the ultraviolet germicidal lamp is colored.

Why lavender?

Because ultraviolet light is outside the purple of the spectrum and close to purple light, the ultraviolet germicidal lamp is purple-blue.