Google has updated its logo structured data markup requirements again, this time to say your logo has to look good on a "purely white background." So you need to test to make sure your logo is visible and I guess attractive on a white background.
The guidelines have this new addition "make sure the image looks how you intend it to look on a purely white background (for example, if the logo is mostly white or gray, it may not look how you want it to look when displayed on a white background)."
We've all seen examples of people uploading logos to a platform and it looking ugly or hard to see when it is placed on the default background color of the background.
Here is Google saying to test the logo on a pure white background.
Google recently updated these same guidelines to say the logo markup now supports ImageObject type.
Forum discussion at Twitter.
