How can QuickTime Player play a mp4 video?

On my Mac, QuickTime Player does not play any of my mp4 videos.

What is your model Mac? What is its version system software? Find out which macOS your Mac is using - Apple Support

It shows correct codecs.

Which codecs are those?

does not play any of my mp4 videos.

None at all? Not even this one?

If all you want is playback, then try VLC or IINA.

If you insist on QuickTime Player compatibility, then that may need some more troubleshooting and analysis.

If a media file doesn't open or play on your Mac, iPhone, or iPad - Apple Support