My hair has got darker as I've got older (no grey), but I used to be blonde, and the colour is draining, as we lose colour in our complexions as we get older. I always had blonde and red highlights, but of course that stopped in lockdown, and I saw my natural colour for the first time in years - I looked dreadful (not helped by the DIY haircut, but that's another story😢).
I took matters into my own hands, and got a box dye from Amazon. It looked better (the dye was a bright dark red), and I was firmly locked down, so nobody saw it other than Mr D and the postman, but when lockdown lifted and I could get an appointment I was keen for something more subtle (plus, it was growing out). My hairdresser was horrified. Box dyes, particularly red ones, can't easily be coloured over, so I had to wait months for it to grow out so I could change the look. He did put highlights in after a while, but had to be very careful as they were a different colour on the red bits.
I now leave well alone, and my hair colour to the expert. It currently has blonde highlights, and I will have lowlights added on my next visit which is next week, I believe. It's less traumatic that way.