Honestly there's enough precedent I'm gonna handwave the tifa thing as a fluke. You barely see her for more then a min in that flashback anyway. Reminds me of somebody using noclip in the original KH and found out kairi had fully modeled panties or something? They took that out for the final mix version that released in Japan a year later.
Lately Nomura and co have George lucased a handful of scenes in kh3 (largely for the better). mostly just changing lighting, textures and models in the ending and for some reason adding a 30 second voiceover cutscene in the Melody of memory song game.
People are theorizing they are experimenting with adding secrets post game via the patches. I'm not sure it's so grandiose but it is interesting. They did add a patch to cut off the ending of kh3 to prevent spoilers from being leaked pre launch. I suspect they did the same with rebirth.
It's likely the leaks are incomplete.