By way of an example, in the Popperian school ideas are metaphysical if they are not falsifiable. So the conservation laws, being neither provable by mere deduction nor falsifiable, are metaphysics. For Watkins this is no more than an evaluation of their logical structure, but others will take this as an insult, not wanting anything in physics to be metaphysical. The conservation laws are not derived only from logic, but from experimenting and theorising over considerable time. — Banno
Yes, the "Meta" label has debatable baggage. Aristotle didn't classify his Nature topics in terms of falsifiability-by-experimentation, but he did divide his book between A. topics that were knowable by observation (Empirical) and B. topics that were knowable by reason & imagination (Theoretical). The latter later became known as "Metaphysics", and concerned concepts that are not directly knowable by the senses, and not verifiable by empirical methods. Most theories, even today, are endlessly arguable.
Later still, empirical science began to develop methods for testing theories*1. But what we call a "Theory" today is still a philosophical generalization (generic class) that can't be verified short of testing all possible instances of the category hypothesized. So modern science still combines Observation (Physics) with Theorization (Metaphysics)*2. Some theories reach a dominant consensus for a while, but remain open to refutation.
Theoretical Metaphysics has been found useful in Science. So, the problem is not its lack of empirical verifiability (e.g. Big Bang ; Multiverse), but with its associated worldview (Materialism vs Idealism). Some form of Big Bang/MV theory can be taken for granted by those who don't accept religious theories (Genesis ; Messiah) on faith. Both types of theories are "Metaphysical" according to Popper. And neither has any confirmable consequences in the here & now Real world.
So, a pre-BB theory (Cosmology) can be judged plausible if it predicts observable post-BB consequences. Inflation Theory was intended to do so, but fell short*3. Both Multiverse and Genesis theories imply some real-world consequences*4. And both are Metaphysical in that they are not directly & conclusively verifiable. Therefore, "what is to count as metaphysics" seems to boil down to whether it supports your own philosophical worldview, or an "erroneous" view.
*1. Scientific theory :
A scientific theory is an explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results. __Wikipedia
*2. Metaphysics of Science :
Metaphysics of Science is the philosophical study of key concepts that figure prominently in science and that, prima facie, stand in need of clarification. It is also concerned with the phenomena that correspond to these concepts. Exemplary topics within Metaphysics of Science include laws of nature, causation, dispositions, natural kinds, possibility and necessity, explanation, reduction, emergence, grounding, and space and time.
https://iep.utm.edu/met-scie/
*3. Is The Inflationary Universe A Scientific Theory? Not Anymore :
And it's even worse, they argue, inflation is not even a scientific theory:
“nflationary cosmology, as we currently understand it, cannot be evaluated using the scientific method.”
https://www.forbes.com/sites/startswith ... 66fd61b45e
*4. Genesis Prophecies :
https://www.icr.org/article/genesis-prophecies