This is what happens when you go out of bounds with noclip without game crashing.
I'm not sure if it needs further research since all it seems to do is lead you to glitch city (when walking to out of bounds horizontally or sometimes vertically) or to duplicate versions of the pokecenter/indoor maps with no objects, NPCs, triggers (when walking to out of bounds vertically).
Do you remember when you try to walk out of bounds with noclip cheat on, the game crashes? (I do) well I modified the code that makes the game ignore transitioning to map 255 (the one that causes the crash) and added enhanced noclip (tile collision is disabled but you can still interact with everything normally). This can't be achieved using regular cheat codes.
But I don't know what those tiles are that makes the player disappear when you walk into them and then re-appear when you walk out of them (not to mention that they also locks player's facing direction too) like you saw in the video. (Maybe they're holes?)
I made these patches which makes "walking out of bounds without game crashing" possible (non-debug mode and debug mode):
https://drive.google.com/drive/folders/1ko5zIwbmU_FLpzh9iQ1CGROoXrxdJ_2i?usp=sharing