It used to work pretty fine but for some time it doesn't work at all. Still all webp images are accepted.

It's worked great for the most part for years now but seems to not work on some sites for whatever reasons. Updated, and I tried changing settings back and forth but some sites it just does not work on. Imgur for example, it wont work if I'm on the main page, but if I go ahead and click on an image and then try it , it works. odd. Seem to be finding more sites it just does not work on lately, but it still works on most at least.

Doesn't seem to work. I've selected strip webp and avif, but both the developer console and https://www.whatismybrowser.com/detect/what-http-headers-is-my-browser-sending say I'm still sending webp and avif in the Accept header.

Edit: Strangely, toggling the "Run in Private Windows" to "Allow" and back to "Don't allow" (which is my desired setting) fixed the issue, even though I always ran the tests in normal browsing instead of private browsing. I'm unable to replicate this for a proper bug report, but just a FYI for others facing similar issues.