Bug report:
I did not see a place to file a GitHub issue for fedibird so I write it here.
The WebP support is incomplete. There should be a thumbnail image generated, but there isn't.
So after uploading a WebP image, the compose form looks like the second pic:
(The first pic is the WebP image uploaded to fedibird.)
@noellabo The "original" size image still exists. It's been converted to jpg. You can check the file by clicking the first image to enlarge.
@noellabo I proposed another issue with possible fix on GitHub. https://github.com/fedibird/mastodon/issues/1