Hello @jesus.rosales
The format of the exported data from K10 is not a single file, there are repository folders for data and metada with hundred of files inside, that are not actually 1:1 copy of your files they have a specific format for K10 to maintain those repositories. These files were compressed and deduplicated, and they can have references between repositories from different dates.
That being said I think that running a diff command on Minio between those repositories will not give you any useful real data regarding differences between restore points.
I would not use this as a retention check, the recommended way is to check your restore points for the application on K10 dashboard, there you can see how many versions you have and the dates and compare with your retention setup in the policy.
Hope it answer your question.
Rubens