Not trying to be picky but

Letterbox? Do the devs even know what letterbox is? This app, as far as I know, is not designed for a CRT so it’s bewildering the developers of one of the best media players in the world don’t know the definitions about said media

Letterbox doesn’t mean it’s for a CRT.
It just means the picture should be displayed in its entirety – if the video and screen aspect ratio don’t match, there’ll be black bars (boxing the picture).

  • for older content in 4:3 resolution, that means you’re getting black bars to the left and right
  • for cinematic content that’s shot/distributed in 21:9, that means you’re getting black bars to the top/bottom of the video.

Yes but probably something like “Original” would be a better wording for this.

The resulting video-graphic image has mattes of empty space above and below it

yea…