Apple Watch strap turning green

I’ve read another post regarding the same.

I have a genuine Apple Watch strap Lilac, i haven’t worn it for a while and now it’s starting to go green.

does anyone know why this is happening? I don’t ware anything green for dye to transfer etc.

at £50 a strap I don’t expect this from Apple, I can’t replace it as now it’s obsolete colour.

does anyone have any tips to remove the stain, I’ve tried acetone with no effect.