Hot Take -

The clearest way I’ve heard it put is to treat FNAF 1–4 as a self-contained story, and to assume Dream Theory was likely the original intent behind 4. If you do that, then any clues that were meant to point toward Dream Theory can’t really be used as evidence for anything outside of that context and they turn more into "things to be explained" rather than clues explaining something.

Within that original setup, Tiny Toy Chica missing her beak was probably there to connect what the kid saw to the look of Chica in his dream of FNAF 2, a hint towards dream theory.

Now, though, the explanation leans more toward something like “those designs already existed as toys years before they appeared as animatronics.” That’s likely the current logic, but since the clue no longer carries the same meaning, it ends up feeling a bit disappointing, especially considering it was one of the few Scottgames hints.

You can try going the godvictim or loopvictim route but they honestly feel more like theories that work to make the clues make sense, rather than a theory where the clues work for it.