Shimmering lights purple shampoo or just any Purple shampoo makes my hair turn grey?

How come whenever i use Shimmering lights purple shampoo or just any Purple shampoo, it makes my hair turn grey? I dont even leave it in for long, maybe for less than a minute at times

Nylah Castillo: It “over tones” your hair…. The color will go away. Don’t use it every wash it’s drying too.

Harmony Fletcher: Your hair may be super porous

Maeve Harrison: what is a way to fix that

Harmony Fletcher: Regular deep conditioning treatments

Ariah Snyder: Do you use it every day?

Maeve Harrison: no like once every 2 weeks

Ariah Snyder: I only use it when I notice my blonde has yellow in it usually that’s about when my hair needs done at the four or five week mark are you washing your hair with super hot water?

Milani Holloway: Dilute it with another shampoo

Lilith Parsons: You’re hair is porous. Protein treatments will help fill in those little holes.

Addyson Stevenson: Because damaged porous hair will suck up pigment like a dry sponge.

Elise Lamb: I use it once a week & either shampoo with regular shampoo after or put it o while.i.have conditioner in so it doesn’t grab as bad