Sure, but the US constitution also prevents "taking" without compensation. That "taking" can also include you keeping the property but the government imposing new rules that lower it's value.
Do you have an example? I'm not aware of any instance of a general change that lowers property values causing the gov't to have to compensate landowners. The "taking" of which I'm aware is use of eminent domain to expropriate land, which requires fair compensation to the owner.
True, but this is a case where a difference in degree becomes a difference in kind. There’s a huge difference between “taxes are higher this year” and “taxes will be specifically levied in a way to make that asset of yours worthless”. Generally, the latter is considered a taking that merits compensation like in the case of eminent domain.
Yes, but it’s worthless to the owner on the market, as the entire point of Georgism is to drive said land value to zero. Yes, people would pay for it, but those payments would not go to the owner, as they would be diverted to the government via tax, functionally the same as if a tax made your retirement account worthless.