Entropy is not absolute!

The entropy of some data is well-defined with respect to a model, but the model choice is free. I.e. different models will assign different entropy to the same data.

And how do we choose a model...? Well, formally by minimizing the information needed to describe both the model and data (the sum of model complexity and data entropy under the model) [1]

You might argue that's all too information-theoretic and in physics there simply is an objective count of the state-space, a maximum entropy, and so on. Alas, there is not even general consensus on whether there is a locally finite number of degrees of freedom.

[1]: https://en.wikipedia.org/wiki/Minimum_description_length