The proposed fees for a sovereign fund are not a tax; they are rent, just like the monopoly holders of copyrighted and patented IP charge rent for using that IP. The foundation of why an IP holder or user should pay rent to society is that no IP is ever generated from nothing. It's all based on the work that comes before. As I said, all IP is part of a common pool. For example, many drugs result from research funded by governments. That research is based on something discovered previously. Pharmaceutical companies take that research for free and make obscene profits. They should be paying into a pool that could be used to pay for more study or benefit society in other ways.
The same is true of art. Artists train on the works of others and then incorporate the techniques and perspectives into their own work. This is why there are "schools" of art—a collection of artists who use the same or similar techniques to produce art. The Impressionists, Pointillists, abstract, Hudson River Valley, pastoral—art is also not limited to Homo sapiens. Earlier hominids have left behind similar works on cave walls or carved shapes. Elephants are another creature that creates art.
We don't need to significantly restrict or change IP protections. Semiconductor manufacturers use this practice. See https://www.jedec.org/about-jedec/patent-policy. This should become standard for all protected IP. You get paid for it but you can't restrict what people do with it. This could benefit society in many ways, for example, lower-cost pharmaceuticals. Third parties could make the same drug as the original discoverer, and they can do it at a lower price than more profit. One thing we need to protect against is the equivalent of patent trolls—someone "inventing" something and claiming part of the FRAND licensing pool without actually producing something themselves.
Yes, intellectual and physical labor are different. If you dig a ditch, you can't claim IP protection and extract rent from all ditch diggers for it. However, many people, including myself, have discovered that the results of our intellectual labor was created by somebody else earlier. This is why the patent office has a first-to-file rule. As a society, we need more intellectual honesty and effort to determine whether a piece of IP unique enough to be worth protecting. I also think we need to expand IP protections to AI-generated intellectual labor.