

Unfortunately, currently Microsoft Edge does not support avif format files due to design. The closest I can find to an official comment from Microsoft is from XuDong Peng-MSFT in this answer, in which they give this rather cryptic and vague reason: Suggestions of a flag to enable AVIF support appear to have been hallucinated - they do not work, nor are they documented by Microsoft anywhere.

The AV1 Video Extension does not enable AVIF image support in Edge. Microsoft have not stated anywhere they are working on it. Microsoft have no official status on AVIF support.

I cannot find any official word from Microsoft on it. The correct answer here is that we simply don't know as of. See here: on licensing things to clear up. It is a licensing issue holding things up. Alex Russell, Microsoft Partner PM on the Edge team and a Blink API owner has provided an update.
