Why is there a new hash every time a file is transferred?

Question

Hashing

Good afternoon.
I transfer the file to the disk (smart gives all the rules without problems) (from another disk or, for example, from the cloud) and each time the file is transferred, it turns out with a completely different md5 (transferred 5 times - received 5 different hashes on the recipient disk).
With what it can be connected and how it is possible to be convinced of it (how to check up)?