Laravel request file extension different then the submitted Blob

I recorded an audio in my Chrome browser and that results in a Blob:

But when I submit this to my Laravel application like this:

$name = implode('.', [str_random(65), $request->file('audio')->extension()]);
Storage::disk('s3')->putFileAs('files', $request->file('audio'), $name);
$mime = $request->file($file)->getMimeType(); 

The extension is: .webm instead of .mp3 And the mime type is video/webm instead of audio/mp3.

via Chebli Mohamed