I'm far from an expert in this field--indeed, I can but barely grasp the gentle introductions to these topics--but my understanding is that calling string theory a "theory of everything" really flatters it. String theory isn't a theory; it's a framework for building theories. And no one (to my understanding) has been able to put forward a theory using string theory that can actually incorporate the Standard Model and General Relativity running in our universe to make any prediction in the first place, much less one that is testable.

Getting into the weeds about what is and is not "A Theory" is an armchair scientist activity, it's not a useful exercise. Nobody in the business of doing physics cares or grants "theory status" to a set of models or ideas.

Some physicists have been trying to build an updated model of the universe based on mathematical objects that can be described as little vibrating strings. They've not been successful in closing the loop and constructing a model that actually describes reality accurately, but they've done a lot of work that wasn't necessarily all to waste.

It's probably either just the wrong abstraction or missing some fundamental changes that would make it accurate.

It would also be tremendously helpful if we had some new physics where there was a significant difference between an experiment and either GR or the standard model. Unfortunately the standard model keeps being proven right.