Any time you "copy" an image by right-clicking "Copy image" in a browser, you're copying a raw bitmap representation of the image, not the actual file served. This is quite sensibly automatically converted to a nice lossless PNG when pasted to most locations. Absolutely nothing to do with Google.
webp is better btw, better compression ratios, transparency in lossy images, transparency in animated images, more customization for animation settings than gif, and only one file extension needed for all these benefits!