Board Thread:Support Requests - Getting Technical/@comment-5621219-20170217100518/@comment-126761-20170322170600

WebP images are only used in supporting browsers (like Chrome, but not Firefox currently), so browser choice would have some effect. It is possible some images are still cached with the older WebP settings, too.

We are definitely interested in seeing specific examples of problem images, and would encourage anyone to send them in to Special:Contact/bug for us to review.