From plum to pastel?

Plum always goes turquoise on me when bleached. Is that Plum next to the bleached roots? I am surprised it is pink and not green.
Plum dilutes to a pinky lavender colour when diluted, so you may need to add more blue if you want it to act as a toner. It is also very strongly pigmented so you need to dilute it a lot for pastels.

ETA It was the old formula that dilutes to a pinky colour, the new one may be different. The fact that your hair is so pink was making me think you have the old formula.

If it goes turquoise then it's not a smart idea to bleach it in order to get lavender...unless i use candy pink on top of it, i guess.
That's not plum, it's atomic pink from Speccial Effects but i couldn't find a newer picture of my roots, sorry for that! It may have been misleading!

This new formula is a bit too blue, so it's really confusing...OTL

The new plum diluted to pastel is very blue, rather a pastel blue (but a 'darker' blue, not an icy blue), not very purple. I tried this because my dye is taking it's time getting here. On a near white base and it was more blue than purple too.

If your roots are yellow like that, I'd say it's still too dark of a yellow. But pictures might be deceiving. My hair, when it was yellow like that, barely toned with purple shampoo (the very potent bonacure). The very diluted plum mixture didn't take on that yellow either. I don't know how light a pastel you want, though.

The new plum diluted to pastel is very blue, rather a pastel blue (but a 'darker' blue, not an icy blue), not very purple. I tried this because my dye is taking it's time getting here. On a near white base and it was more blue than purple too.

If your roots are yellow like that, I'd say it's still too dark of a yellow. But pictures might be deceiving. My hair, when it was yellow like that, barely toned with purple shampoo (the very potent bonacure). The very diluted plum mixture didn't take on that yellow either. I don't know how light a pastel you want, though.

Should i mix some pastel pink with the diluted plum, then? Or maybe just see how it goes and keep some pink at hand to fix it?

I don't want my hair to be almost white, or with barely a hint of color in it, i want it to be pastel but still look pigmented...if that makes sense.
They do look really yellow, but because of the intagram filter, the actual color is more like inside-banana- yellow.

Ah that makes a lot more sense lol!
Lilac  shades on yellow hair come out either ash blonde or silver (as it tones the yellow out) depending on the depth of the yellow, so you need to go slightly darker for the lilac to show.
If you do decide to bleach out the Plum, you can still achieve a lilac over a pale turquoise base. My base was faded Directions Turquoise, so i just mixed the lilac with more pink to balance out the green tones. I use Plum as my main colour for diluting, but i have a stash of the old pink based formula lol. Every time I do my roots I get a ring of turquoise from washing the bleach out, so I put a blue toned lilac on the newly bleached parts first as a toner, then a pinky lilac over the top. It is fiddly, but i loved having pastel purple hair so it was worth it.

Ah that makes a lot more sense lol!
Lilac  shades on yellow hair come out either ash blonde or silver (as it tones the yellow out) depending on the depth of the yellow, so you need to go slightly darker for the lilac to show.
If you do decide to bleach out the Plum, you can still achieve a lilac over a pale turquoise base. My base was faded Directions Turquoise, so i just mixed the lilac with more pink to balance out the green tones. I use Plum as my main colour for diluting, but i have a stash of the old pink based formula lol. Every time I do my roots I get a ring of turquoise from washing the bleach out, so I put a blue toned lilac on the newly bleached parts first as a toner, then a pinky lilac over the top. It is fiddly, but i loved having pastel purple hair so it was worth it.

That sure is tricky...but worth a try! Thanks ♥
Luckily i've still got some leftover atomic pink from SFXs, so i'll mix that with the diluted plum to make the right shade to tone down the turquoise (in case it comes out that way when bleached) and will definetly try to make it slightly more pigmented than i want it to be...

I wish they had not changed the Plum formula, it's much more difficult to change color this way!

I know, it really sucks! i don't know what I will do when I use up my supply of old Plum.
I always mixed my own pastel purples, I tried Directions Lilac straight out of the tub once and it was expensive (I have a lot of hair so needed 3 tubs) and didn't last very long before fading to a blue. My favourite mixes have been Plum/Neon Blue/Rose Red in various proportions.