The image library now has a page of its own at Your images, in the account menu beside Your teams. It lists every image stored in your account, with the same search, format filter and sort order as the image picker, and shows how much of your storage allowance is used.
Each image can be opened at full size, have its address copied, or be deleted. Uploading from this page adds to the same library the picker uses, so an image uploaded here is available in Notes, Website Builder, Books, Store and every other tool that accepts a picture.
The library belongs to your account rather than to a team, so it holds the same images whichever team you are working in.