`FFmpegFixupM3u8PP` may need to run with ffmpeg

Bug in 62b5c94cad
Closes #7725

yt_dlp/YoutubeDL.py

@@ -3450,10 +3450,11 @@ class YoutubeDL:
                     postprocessed_by_ffmpeg = info_dict.get('requested_formats') or any((
                         isinstance(pp, FFmpegVideoConvertorPP)
                         and resolve_recode_mapping(ext, pp.mapping)[0] not in (ext, None)
-                    ) for pp in self._pps['post_process']) or fd == FFmpegFD
+                    ) for pp in self._pps['post_process'])
 
                     if not postprocessed_by_ffmpeg:
-                        ffmpeg_fixup(ext == 'm4a' and info_dict.get('container') == 'm4a_dash',
+                        ffmpeg_fixup(fd != FFmpegFD and ext == 'm4a'
+                                     and info_dict.get('container') == 'm4a_dash',
                                      'writing DASH m4a. Only some players support this container',
                                      FFmpegFixupM4aPP)
                         ffmpeg_fixup(downloader == 'hlsnative' and not self.params.get('hls_use_mpegts')