[Europan Ocean (OP)]

When an object such as a planet, falls into a black hole, is entropy reversed and is work done of any kind or are there any extraordinary phenomena, reversing decomposition...?

[Kryptid]

There's no reason that it would reverse entropy. The planet gets destroyed, which would increase entropy.

[evan_au]

As well as chemical entropy, and entropy of physical systems (eg gases), there is also entropy of information.
- There is a principle in quantum theory that information cannot be destroyed.
- At one time, it was thought that information would be destroyed in a black hole, which would increase information entropy
- That paradox is still not resolved, but Hawking radiation may provide a partial solution
- More exotic solutions have been proposed, such as there being an independent universe with its own spacetime inside the event horizon

See: https://en.wikipedia.org/wiki/Black_hole_information_paradox#Relevant_principles