Google AdSense publishers started complaining yesterday that many of their colorful ad units on their web sites went from bright colors to a muted and toned down gray look.

A WebmasterWorld thread has several complaints all in the same tone as this one:

Here is a picture of an ad unit that went gray on one publisher, who posted this on Twitter:

I don’t see the gray ad units this morning but it seems like it was an issue throughout most of yesterday and now things have reverted back to normal. Did you notice this?

Forum discussion at WebmasterWorld.