The image at File:Cincinnati Bell logo.png does not contain a white background. However, on the actual image at Cincinnati Bell has a white background. Looking at any resized version of the image seems to contain a white background. I downloaded the image itself, and the reduced file contains a white background.
There seems to be something wrong with the PNG resize path, likely due to indexed PNG images. This appears to be a regression, as I have been uploading indexed PNGs when appropriate for a long time, and they have always resized correctly.