I've used "Black Medallion" mulch for years but only as edging around my beds. It starts out black, then when spread for a day, turns brown, then eventually leaches out to a brownish/grey.

Are you speaking of some new type of mulch just on the market?
I might have older photos because I haven't spread any yet this season. I'll try to find some.

That probably should have been "leeches" out to brwn/grey..

The mulch is dyed black but I decided against it after reading about the dye. I went with a dark natural brown. I hope it doesn't fade to much. The beds are new and the plants are still small so I needed to suppress the weeds.

I am glad to read you decided to skip the dyed mulch. I am always a bit mistrustful of dyed mulches, both because of the dye itself and also since dye can be used to hide wood from construction debris, etc mixed into the mulch. (Not that it always is, but I can't tell.)

IME, if the mulch fades, stir it up a bit since the lower layers keep their color better. Alternatively, just add a very thin new layer. If you haven't yet spread it, putting a layer of cardboard or several layers of newspaper under the mulch helps block light and prevent weeds in a new bed. The under layer will decompose relatively quickly, but will help while the mulch is knitting together.

I never thought about construction debris as an ingredient in some dyed mulches. Makes perfect sense they'd so something like that. ugh.

I saw a bag of mulch today that read "Enhanced True Brown". :(