I spent a few minutes skimming the paper, and it doesn't say much new. By definition, you cannot falsify a quantum interpretation. That is why they are philosophy, not physics.

First let me start off with what is falsified. The most naive possible version of the Copenhagen interpretation is that, whenever a system interacts with another, wavefunction collapse occurs; the larger system has "measured" the smaller one. This is not a legitimate interpretation, but a placeholder for one that's good enough to get you through a first course in quantum mechanics. It's clearly not true and I've never seen any text suggest otherwise.

We know naive Copenhagen isn't true because it directly conflicts with observation. For example, you can pass a photon through a beam splitter, or steer a particle with a magnetic field, without collapsing superpositions. And we entangle the states of two systems all the time, which would be impossible if interaction were automatically a measurement.

The real Copenhagen interpretation is much more agnostic about what counts as a measurement. There's no criterion like "interacting with a system with more than X degrees of freedom causes collapse", but it is agreed that interaction with a macroscopic, thermodynamic system does count as a measurement. The crucial difference between this and naive Copenhagen is that, like all proper interpretations of quantum mechanics, it isn't falsifiable. In principle one could tell between many worlds and Copenhagen by, say, running Wigner's friend backwards in time, but this is impossible by the Second Law of Thermodynamics. Undoing the interactions of a trillion trillion molecules is more impossible than anything ever dreamt of in science fiction.

It seems like this paper is another variation on this old story. The point is, if the "experimenters" in the paper's thought experiment are microscopic, then all legitimate interpretations (i.e. everything but naive Copenhagen) completely agree on what happens: unitary evolution by the Schrodinger equation. If the experimenters are macroscopic, then you can get technically get logical contradictions from Copenhagen collapse, and it's not hard to do this, but by thermodynamics you can never observe them. So the paper tells us nothing about physics.

The paper does say something, but it's purely philosophical. It tells us that if you want to take the stance of a philosopher, and not worry about what is physically observable but just ponder the logical aesthetics of the postulates, then from this God's eye view everything besides Many Worlds has a sharp, ugly feature. But once you get to debating this kind of thing, you've lost all hope of objectivity: diehard proponents of every interpretation think all the others are aesthetically unacceptable. (Copenhagen people hate the ontological extravagance of Many Worlds, pilot wave people really really want their particles to have definite positions, etc.) So in either case the paper does not make a knock-down argument against anything.

I spent a few minutes skimming the paper, and it doesn't say much new. By definition, you cannot falsify a quantum interpretation. That is why they are philosophy, not physics.

First let me start off with what is falsified. The most naive possible version of the Copenhagen interpretation is that, whenever a system interacts with another, wavefunction collapse occurs; the larger system has "measured" the smaller one. This is not a legitimate interpretation, but a placeholder for one that's good enough to get you through a first course in quantum mechanics. It's clearly not true and I've never seen any text suggest otherwise.

We know naive Copenhagen isn't true because it directly conflicts with observation. For example, you can pass a photon through a beam splitter, or steer a particle with a magnetic field, without collapsing superpositions. And we entangle the states of two systems all the time, which would be impossible if interaction were automatically a measurement.

The real Copenhagen interpretation is much more agnostic about what counts as a measurement. There's no criterion like "interacting with a system with more than X degrees of freedom causes collapse", but it is agreed that interaction with a macroscopic, thermodynamic system does count as a measurement. The crucial difference between this and naive Copenhagen is that, like all proper interpretations of quantum mechanics, it isn't falsifiable. In principle one could tell between many worlds and Copenhagen by, say, running Wigner's friend backwards in time, but this is extravagantly impossible by the Second Law of Thermodynamics. Undoing the interactions of a trillion trillion molecules is more impossible than anything ever dreamt of in science fiction.

It seems like this paper is another variation on this old story. The point is, if the "experimenters" in the paper's thought experiment are microscopic, then all legitimate interpretations (i.e. everything but naive Copenhagen) completely agree on what happens: unitary evolution by the Schrodinger equation. If the experimenters are macroscopic, then you can get technically get logical contradictions from Copenhagen collapse, and it's not hard to do this, but by thermodynamics you can never observe them. So the paper tells us nothing about physics.

The paper does say something, but it's purely philosophical. It tells us that if you want to take the stance of a philosopher, and not worry about what is physically observable but just ponder the logical aesthetics of the postulates, then from this God's eye view everything besides Many Worlds has a sharp, ugly feature. But once you get to debating this kind of thing, you've lost all hope of objectivity: diehard proponents of every interpretation think all the others are aesthetically unacceptable. (Copenhagen people hate the ontological extravagance of Many Worlds, pilot wave people really really want their particles to have definite positions, etc.) So in either case the paper does not make a knock-down argument against anything.