Resolution switching broken on Shield 8.2.0?

My wife has been watching episodes of old TV shows and the resolution of the files are 640x480 (4:3). When I have Resolution Switching enabled in the settings on Plex, the video is stretched out and has black bars on both the top and bottom of the screen and on the sides, instead of just the sides since it is 4:3. I've tried changing the playback settings but changing from original to letterbox does not do anything. If I switch off Resolution Switching in the Plex settings, the video displays normally. This is happening on both my 2017 shield pro and my 2019 tube Shield. Has anyone else experienced this?

Also, can someone explain to me what Resolution Switching actually does? I've always had it enabled, but not sure what the point of it is.