> Do you mean the file extension should only reflect the file format and not the codecs it has inside ?
That's pretty much always been the case. File extensions are just not expressive enough to capture all the nuances of audio and video codecs. MIME types are a bit better.
Audio is a bit of an exception with the popularity of MP3 (which is both a codec and a relatively minimal container format for it).
Easier said than done, when there's no commonly accepted standard to store a file's MIME type as metadata, and you don't want to load all of ffmpeg into every webserver or file browser just so it can expose the proper granular one.
That's pretty much always been the case. File extensions are just not expressive enough to capture all the nuances of audio and video codecs. MIME types are a bit better.
Audio is a bit of an exception with the popularity of MP3 (which is both a codec and a relatively minimal container format for it).