It’s not new. My (excellent) braider often used soft pastels, usually pale blue or lavender, on my grey. The chestnut with sort of lighter mane and tail got a soft green (not lime) or a tan. It was tons easier to unbraid. We are talking high quality braids, and lots of them, on the neck and thin yarn, you couldn’t really tell from further then 10 feet away.
In my barn, even on full care, it was expected clients would unbraid their own. With the sale horses, horses whose owners were not there using a Pro or kid catch rider and Ponies whose tiny riders weren’t yet up to intricate use of the seam ripper? The grooms had enough to do and appreciated being able to see the yarn.
I sometimes see some really clunky braids with not so neatly placed thick yarn, always makes me think why bother braiding if you can’t do better.