So I have had my mid brown long hair highlighted blonde for years and years and never had an issue (same hair stylist).
I had a baby just before covid and then it's been a weird year so I've only had my hair coloured in September 2019, May 2020, then a couple of weeks ago.
Where my roots were so dark the colour at the top has some brassy tones throughout. Stylist put a toner on and I've been using an intensive purple shampoo since but it's not shifting.
Hopefully this won't be a problem long term as I'll be able to have regular colours again
Any suggestions for the interim?