We have discovered recently that copying a D365 instance can have some issues with regards to PA/Flows that are contained in the instance. These issues are not documented on the Copy an environment page, which is where you would expect such issues to be, and is the documentation we followed in implementing this change. Instead, they are documented on the Solutions Overview page, which has no bearing on the process of copying an instance. That page states:
Database operations such as backup, restore, and copy are not supported for canvas apps and flows. These operations can corrupt canvas apps and flows.
From this I would highlight the following.
This should be documented on the "Copy an environment" page as that is the most logical page someone would turn to for performing such an action.
The idea that backup and restore could corrupt such components lessens the viability of these methods being used as a valid rollback option. For this reason alone I would put forward that this issue should be fixed as a matter of priority.