That's interesting, I bet it's due to the dyes being worse for the environment or something.
Now N goes through phases of over-buying stuff, and at one point we had something like over a hundred loo rolls in stock (this wasn't during COVID I hasten to add!) and they were all colours of the rainbow - well a pastel rainbow, at least - that was a long time ago but since we've been living here, so I reckon between 15-18 years ago.
It hadn't actually occurred to me that I hadn't seen coloured ones in the supermarket for a bit, but that's because we tend to buy the cheap ones.