See for example bug #55523, there I have uploaded images in PNG and JPG format and both sets of images have been mangled by Bugzilla. The original images display perfectly fine in my browser.
*** This bug has been marked as a duplicate of bug 55506 ***
Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.