As noted in the related issue that you link to, there is not meant to be a deactivate.ps1 script - the deactivate command is provided via a global deactivate function created when you run activate.ps1 (although this is an implementation detail, all that matters is that a "deactivate" command exists, not how it is implemented).

The documentation of the implementation-specific behaviour is incorrect, but as it's describing internal implementation details, it shouldn't be relied on anyway.

Suggested documentation fix:

"""
You can deactivate a virtual environment by typing “deactivate” in your shell. The exact mechanism is platform-specific and is an internal implementation detail (typically a script of shell function will be used).
"""