Yes, the NexusMods site ignores the change made by this add-on. But for me, the .png file saved from Chrome is the same WEBP file -- with a .png extension.

If you hear of any way to fool the site, I can try to implement it. Until then, when you are viewing the image in its own tab, you can get Firefox to download it as a PNG by using the built-in screenshot tool. Either right-click the blank area above/below the image > Take Screenshot, or use the keyboard shortcut (on Windows, Ctrl+Shift+S). Then move the mouse toward the upper left of the image and a dashed rectangle should appear around the image. Click to select the image, then click the Download button. The file name is a mess, but it will be a true PNG file.

Hi, there is one new permission in version 0.9, the "management" permission, which allows checking the names of your installed add-ons and whether they are enabled or disabled. You can see the added code in the comparison page on Github: https://github.com/jscher2000/dont-accept-webp/commit/25eea9332a3819f5d0c9c224b7178bd3db830694

If anyone prefers to install the previous version, you can grab it from the All Versions page at: https://addons.mozilla.org/firefox/addon/dont-accept-webp/versions/

And if you do not trust me, don't run my add-ons.

The extension should discourage servers from recompressing JPG and PNG images as WebP images -- typically without changing the file name/extension. Can you share a URL of a page that recompresses JPG and PNG images despite the extension? Perhaps I can figure out a workaround.

In case the problem is cached images from a previous visit to the page, you can clear Firefox's web cache: https://support.mozilla.org/kb/how-clear-firefox-cache

Note: the extension doesn't block pages like https://developers.google.com/speed/webp/gallery1 from using WebP images when they are part of the design.